Why does email bounce?

Email can bounce for many reasons. I'll look at several of the most common mail bounce messages, and try to interpret what they really mean.

Sometimes, my email bounces. Every so often, I’ll send a message, and a short time later, I’ll receive a reply saying that the email failed to go through. Why does it happen? And how do I fix it?

Well, I’m afraid there are many reasons why mail can bounce. In fact, there are so many ways it could fail, that sometimes I’m amazed it works at all. But it definitely works most of the time, and one of the ways that it works is that very bounce message that you get.

You see, there’s gold in that bounce message. It’s not only telling you that your message didn’t go through, but if you look a little closer, you’ll see it’s trying to tell you why.

Examining an email bounce

Email bounce messages vary in format and exact wording, depending on the mail server sending the message back to you. Different types of mail servers use different terminology. Some are quite geeky and difficult to understand. Others seem to take five paragraphs to tell you that you probably mistyped the email address.

What I’ll do here is list some of the most common messages, what they mean, and what you can do. Remember, though – a message you get may not be worded exactly as I list it here. Look carefully at the bounce message you receive and see which of these it’s most like.

First, let’s look at a couple of bounce messages. Buried in the all the geekery, I’ve highlighted a couple of important things.

   ----- The following addresses had permanent fatal errors -----
    (reason: 553 sorry, relaying denied from your location
     [] (#5.7))

   ----- Transcript of session follows -----
... while talking to smtp.example.net.:
>>>> DATA
<<< 553 sorry, relaying denied from your location 
[] (#5.7.1)
550 5.1.1 <somewhere@example.com>... User unknown
<<< 503 RCPT first (#5.5.1)

Here’s a bounce from another mail server that attempts to be more friendly:

Hi. This is the qmail-send program at example.com.
I'm afraid I wasn't able to deliver your message to 
the following addresses.
This is a permanent error; I've given up. 
Sorry it didn't work out.

<somewhere@example.com>: does not like recipient.
Remote host said: 550 MAILBOX NOT FOUND
Giving up on

The words”MAILBOX NOT FOUND” or “User unknown” are key, and might actually be expressed in different words, depending on the reason for the failure. Note that the email bounce message includes the email address you were attempting to send to.

Why does email bounce?Common error messages

Mailbox Not Found, invalid mailbox, User unknown, not our customer.

These are all saying pretty much the same thing. In the “someone@example.com” bounce examples above, the mail server “example.com” doesn’t have an account for anyone with the email name “someone”. A couple of common reasons:

  • You typed the email address wrong. The single most common reason this error happens is simply that you made a typographical error in the email address. Check the entire email address for error.
  • It’s an old email address that’s no longer in use. Perhaps the person you’re attempting to email has changed their email address, and you’re using an old one which is no longer valid. Make sure that what you’re using is up to date.

Mailbox unavailable

Nine times out of 10, this is the same as “mailbox not found.” The other 10% of the time it could mean there’s a problem with the recipient’s email account. What kind of problem is hard to say.

Check to make sure you have the email address correct, wait a while, and try again; if it still bounces, contact the recipient some other way.

Mailbox full, Quota Exceeded

Sometimes this will show up as a part of a “Mailbox unavailable” message. It’s fairly clear, though: your recipient has too much email, and their server isn’t accepting any more. This is common with services that limit how much mail you can accumulate.

This can also be a sign of an abandoned account – someone’s stopped looking at and cleaning out their email. In any case, you need to contact your recipient through some other email account, or in some other way.

Host unknown, Domain Lookup Failed

This means that the mail server you’re attempting to use – the “example.com” part, in the examples above – doesn’t exist. A common reason, again, is a typo on your part. Make sure you typed it in correctly.

Another reason is that ISPs change their name. The largest example of this in recent memory was when “attbi.com” changed to “comcast.com”. Anyone trying to send to an old “attbi.com” email address might get this message in return.

Unable to Relay

This is a terribly obscure error message that is becoming more and more common as ISPs try to crack down on spam. Email is sent by relay from one server to the next. There may be many servers involved, but typically, it’s the mail server at your ISP relaying your email to the mail server at your recipient’s ISP.

In general, a mail server must directly “know” either the sender of an email or its recipient in order to safely transmit mail. Mail servers that do not enforce this requirement are called “open relays,” and are exploited by spammers to send out tons of spam.

Things get complicated because not all ISPs agree on what it means to “know” the sender of an email. All of these might result in an “unable to relay” message, depending entirely on the servers and ISPs involved:

  • The “From” address might not match an account on the email server.
  • The ISP might require that email come via a connection (dial up or DSL) actually provided by the ISP: sending using someone else’s connection might not be allowed.
  • The ISP might require you to authenticate before sending email, and you haven’t.
  • A mail server somewhere could be misconfigured.

There’s no blanket answer if “unable to relay” happens only occasionally. Always start by double-checking the email address you’re sending to.

Temporary Errors

Errors like “no adequate servers”, “Connection Timed Out”, “Resources temporarily unavailable”, and “Out of memory” all typically indicate a problem with a mail server that you probably have no control over. They are, in general, temporary, and should resolve themselves over time.

Look carefully at the bounce message; the email server involved may continue to automatically try to deliver your email without any action required on your part.

Blacklist Filters

If you see messages that indicate your email was “blocked,” or “listed in,” and references to sites that have things like “spamcop”, “dynablock”, “blackhole”, “spamhaus”, and similar in their names, then your email was probably intentionally blocked because the receiving system thinks your ISP’s mail server is a source of spam.

Various blacklisting services try to identify servers which are sources of spam. They then make that list available to ISPs, who in turn can block email coming from these sources. The problem is that criteria for addition and removal from these blacklists is vague, at best, and getting a server removed from blacklists can be very difficult.

If this happens to mail that you send, get in touch with your ISP and explain that their server may be on a blacklist somewhere, and then try to use a different email address, or a different email account of your own, to contact your intended recipient. You might also tell your recipient that their ISP is improperly blocking legitimate email.

Content filters

Much like blacklists, content filters are an approach many ISPs now implement to stem the tide of spam for their clients. Most will simply discard email that looks like spam, as I discussed in Why is my mail to this person not getting through?, but some servers will actually send a bounce. Phrases in the bounce message like “Message looks like spam”, “Keywords rejected by the antispam content filter”, “Scored too high on spam scale”, and similar means that your email, for whatever reason, tripped the spam filters on the receiving end. Your email looks too much like spam.

What does it mean to “look like spam”? Here, again, things get vague. That definition will vary greatly based on how your recipient’s email server has been configured. Obvious possibilities that contribute to spam-like characteristics are the use of pornographic words or phrases, HTML-formatted email, currently-popular drugs being hawked by spammers, or even looking too much like a sales letter or a scam.

The best approach is to scan the bounce for any clues and then make sure your recipient can get any email by sending a simpler message. Assuming that all works, re-work your message as best you can to not look like spam.

How long is “a while”?

One of the most common solutions for just about any email bounce (after checking that you’re sending to the right address) is “Wait a while and try again.” The email system, while somewhat random, is also somewhat self-healing. If there’s an email server with a problem, chances are it’ll get fixed or eventually bypassed, especially if it belongs to a larger ISP. For temporary problems, as noted above, email servers will typically keep trying for up to four or five days before giving up.

My rule of thumb for trying email again is “one hour, one day, one week.” In other words, try again in an hour. There are classes of problems that will resolve themselves that quickly. If that still fails, then I’ll try again the next day. If that still fails (and my message can wait that long), I’ll try again in a week. If that still fails … I need to find another way to get my message to my recipient.

When an email bounce isn’t really a bounce

Be careful! There’s a class of viruses these days that propagate by “looking like” bounce messages. They instruct you to open an attachment for more information.

Don’t do it, especially if you don’t recall sending the message in the first place. Don’t open any attachment, especially one accompanying what looks like an email bounce, unless you are absolutely positively 100% certain that it’s legitimate.

You may also be getting bounce messages for email that you didn’t send. There’s another class of virus that “spoofs” or fakes the “From” address on email messages; as a result, you could be getting bounce messages that have nothing to do with you. This scenario is sadly common and I’ve written about it in a separate article: Someone’s sending from my email address! How do I stop them?!

Everything bouncing?

Finally, if every email that you send bounces, then you probably have a different problem. Chances are your email client is misconfigured. Double-check outgoing or SMTP server settings and check with your ISP to ensure that you have them set correctly.

This is an update to an article originally posted : January 16, 2005
Footnotes and references

Thank you to Tom Kulzer of AWeber for some of the information incorporated into this article.


  1. Jeff McCulloch

    If I send e-mail to a group in Outlook (POP3 through Yahoo) and one recipient’s e-mail account has reached quota, does that prevent the rest from receiving that mail?

  2. Diana

    I have been trying to send wedding pictures to my husbands aunt and twice now that I have sent it, it has been returned to me. The message I get is that it timed out. What does that mean? How can this problem be fixed? My husband and I want our family to see some of our beautiful wedding pictures and are becoming frustrated. Any assistance you can give us regarding this matter would be appreciated.


    Diana & Mike

  3. Leo

    Timed out implies that the server name (the part after the ‘@’) is wrong or not responding. It’s possible that the mail server is rejecting the email because it’s too big, but that’s usually what it says in the error message when that happens.

    You might try uploading the photos to a picture sharing service (flickr comes to mind), and then emailing a link to your page on that service.

  4. mahesh

    Hello sir..
    MailEnable: Message could not be delivered to some recipients.
    The following recipient(s) could not be reached:

    Reason: Remote SMTP Server Returned: 553 sorry, that domain isn’t in my list of allowed rcpthosts (#5.7.1)

    Reason Code: SMTP Outbound – General Error
    Error Number: 0

    Message headers follow:

    Received: from SERVER ([]) by silvercommunication.net with MailEnable ESMTP; Wed, 07 Dec 2005 11:00:20 +0530
    Subject: test mail
    Date: Wed, 7 Dec 2005 11:01:09 +0530
    MIME-Version: 1.0
    Content-Type: multipart/alternative;
    X-Priority: 3
    X-MSMail-Priority: Normal
    X-Mailer: Microsoft Outlook Express 6.00.2600.0000
    X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000

  5. Leo

    Mahesh: that looks like a server configuration problem. You’ll need to contact the owner of the server you’re using to send mail through.

  6. igor

    can you tell me more about mu error:

    MailEnable: Message Delivery Failure.

    The following recipient(s) could not be reached:

    Recipient: [SMTP:stefcotasevski@mt.net.mk]
    Reason: 354 Enter mail, end with “.” on a line by itself.
    Reason Code: SMTP Outbound – General Error
    Error Number: 0

    Message contents follow:

    Received: from ([]) by home with MailEnable ESMTP; Tue, 10 Jan 2006 01:05:00 +0100
    Received: from for stefcotasevski@mt.net.mk; Tue, 10 Jan 2006 01:04:25 +0100
    Date: Tue, 10 Jan 2006 01:06:47 +0100
    From: Emilijan Nojkovski
    Reply-To: emce@edusoft.com.mk
    X-Mailer: Mozilla 4.76 [en] (Win98; U)
    X-Accept-Language: en
    MIME-Version: 1.0
    To: Stefco Tasevski
    Subject: nova faktura za 2006 001/06
    Content-Type: multipart/mixed;

    This is a multi-part message in MIME format.
    Content-Type: text/plain; charset=us-ascii
    Content-Transfer-Encoding: 7bit

    treba da mu platime na digit 7027.00 denari so ddv

    Content-Type: application/msexcel;
    name=”izvodi za emil do 12(1).05.xls 1.xls”
    Content-Transfer-Encoding: base64
    Content-Disposition: inline;
    filename=”izvodi za emil do 12(1).05.xls 1.xls”

  7. Leo

    If you got it in response to something you sent, it looks like a mailer is having a problem, and you should resend. If you just got it out of the blue, then it’s probably a malfunctioning spambot, and I’d delete it and ignore further.

  8. Pratik

    Hi Leo,
    me too have some problem while sendng mail through persistmail.
    the bounced mail message is as follows
    MailEnable: Message could not be delivered to some recipients.
    The following recipient(s) could not be reached:

    Reason: Remote SMTP Server Returned: 553 sorry, invalid envelope sender in header (#5.7.1)

    Reason Code: SMTP Outbound – General Error
    Error Number: 0

    Message headers follow:

    Received: from neutron.dns-fusion.com ([]) by dns-fusion.com with MailEnable ESMTP; Wed, 18 Jan 2006 05:20:54 -0500

    Please guide me how to sort out this problem.


  9. Fred

    Re: the problem with “invalid envelope sender in header” it sometimes helps if you invoke Secure Authentication in your mail clients Server Settings (Thunderbird: Click on mailbox, then AccountsView Settings For This Account Select the mailbox you’re sending from (if more than one) then Server SettingsUse Secure Authentication (I’ve no idea how to do that in Ou!*?*k. You’ll have to improvise). You may need to uncheck this once the errant e-mail has been sent (if this is what the problem is). It works in some cases. Pity the receiving mail server doesn’t let you know.

  10. Radha

    After sending e-mail I got failure notice which stated that mail folder of the recipient is full. If the recipient corrects this problem will my mail delievered or should I resend it?

  11. Heidi

    If someone is in the military and working undercover, could the government have set up their computer so it cannot receive personal mail? I corresponded for years with someone who was a dear friend and now messages come back saying:
    This is an automatically generated Delivery Status Notification.

    Delivery to the following recipients failed.

    …I am afraid for his safety. Could he have died? What happens when someone dies regarding e-mails? Does someone have to go in and delete their address? I know in the past his computer and phone had to go through certain security checks by his employer. I’m confused and worried.

  12. V RAMESH


    when I try to send mail through lotus notes I get the follwoing error
    rediffmail.com – Mail server mail2.rediffmail.com rejected your mail;
    Message received from mail server:
    553 sorry, invalid envelope sender in header (#5.7.1)

    please advise


  13. Allwyn

    553 sorry, Authentication failed or timed out. Please do get message first to authenticate yourself (#4.4.3).
    some time i get this error message after sending a message to perticular sender to whome i am sending mails last six months.

  14. Sunil Nair

    This is the error message displayed while sending a mail From: System Administrator
    Sent: Thursday, October 12, 2006 7:09 PM
    To: ‘[Email Address Removed]’
    Subject: Undeliverable: cognos 1Q 07

    Your message did not reach some or all of the intended recipients.

    Subject: cognos 1Q 07

    Sent: 10/12/2006 7:09 PM

    The following recipient(s) could not be reached:

    ‘[Email Address Removed]’ on 10/12/2006 7:09 PM

    553 sorry, Authentication failed or timed out. Please do get messages first to authenticate yourself.(#4.4.3)

    but the same is sent if I close and reopen ms outlook and try to resend it

  15. Leo A. Notenboom

    “Authentication failed” – you have not configured outlook with the proper account and password information to be able to send mail.


    Dear Leo,

    If I am correct, you are the only person who has elaborately explained in simple English giving out different reasons for bouncing of e-mail.

    Well Done. A very good article. I enjoyed reading it.

    Thanks for making a layman like me to understand the technical things so simply.

    God Bless you.


    Sankara Narayanan

  17. SusanG

    Here’s a message I got, after I reconfigured my reverse DNS or PTR record. Some senders, some of the time got this message when they tried to email us. Not all external email was bounced, which suggests something spam-blockish about this error.
    What I don’t understand is that the bouncing happened AFTER we made the change to our PTR record. Do you think it’s the aftereffects of reconfiguring a PTR record, and if so, can you explain why this would happen after the change was pushed out (but not before it was fully propagated)? Thanks so much, Susan

    Hi. This is the qmail-send program at hostXXX.ipowerweb.com.
    I’m afraid I wasn’t able to deliver your message to the following addresses.
    This is a permanent error; I’ve given up. Sorry it didn’t work out.

    vdeliver: Invalid or unknown virtual user ‘xxxx’

  18. Kiran Patel

    some time i get this error message after sending a message like…

    553 sorry, Authentication failed or timed out. Please do get messages first to authenticate yourself.(#4.4.3)

    please Help….

  19. Ramesh Velayudhan

    I’m also getting the following error in the bounced mail text. Can anyone please tell me what is happening, and how this can be fixed ? Thanks in advance.

    Hi. This is the qmail-send program at rediffmail.com.
    I’m afraid I wasn’t able to deliver your message to the following
    This is a permanent error; I’ve given up. Sorry it didn’t work out.

    This message is looping: it already has my Delivered-To line. (#5.4.6)

  20. kamlesh

    dear leo,

    I have a complete different issue.

    I am trying to send a mail using mapi application &outlook express.

    When I am attempting to receive mail adresses from database or ini file It’s gives me the #5.1.1 error ie. I am afraiding etc. as mentioned in ur article.

    I am able to send mails properly through hardcore programming bUT i dont want to do that.

    Plz, help me.



  21. Kym


    Great article. Helped me a lot.

    For one domain on our server we are getting a lot of

    “unrouteable mail domain”

    when the site owner sends out a bulk email so she thinks it is our problem. But I am not too sure.

    Any ideas?


  22. Murali

    Hi. This is the qmail-send program at yahoo.com.
    I’m afraid I wasn’t able to deliver your message to the following
    This is a permanent error; I’ve given up. Sorry it didn’t work out.

    : does not like recipient.
    Remote host said: 550 relaying denied for
    Giving up on

  23. Matt

    Hi, this was a very helpful artical…however I have a dillemma. I use a domain name which I purchased. This domain name forwards all my emails to whichever email address I specify. This way, I do not have to alert everyone in the world when I switch ISP’s and can no longer retrieve mail. I simply use email@mydomain.com and viola! i have an email address forever.

    Well, this has worked great up until about 5 months ago. I am now getting all sorts of these “unable to relay” errors. Why can’t I just get them to leave me alone! I am not a spammer! Why can’t I just use the internet the way it was designed to be used, and get the isp’s to just BUTT OUT!!!

  24. Tacha

    Hi Leo,

    I have a client who used to have an email address from her web site that forwarded to her ISP. She has since switched her hosting to my company AND her ISP to a new provider.

    I have setup her web hosting account as I would any other new account and changed her DNS settings to the DNS of the new host. I also setup forwarding for her email that comes into the Web hosting account to her new ISP (which is the same as the old Web hosting site – she wanted to keep info@ as the email username).

    Most of the time things work fine, but ocassionally, she sends me an “unknown user” error message she has received from her friends or clients because the new Web hosting email address forwards the incoming email to the old ISP email address (which bounces correctly) instead of forwarding it to the new ISP email address.

    I am frustrated because I don’t understand how the new account I set up could ever “know” how to forward to the old ISP address. Is there a registry or something that this forwarding information is on? This has been going on for about 6 months now.

    Thanks in advance for any light you can shine on this problem.

  25. Leo Notenboom

    Hash: SHA1

    It *sounds* like stale DNS entry somewhere.

    Did you set up an MX (mail exchange) record for her domain to point to your
    mail server where the forwarding happens? If not you might consider adding one.
    If there’s no MX record mailer mailers are supposed to use the IP of the
    destination domain as the target server, but I’ve always been more comfortable
    adding an explicit MX to say “the mailer for this domain is here”.

    Six months is a long time for a DNS entry to be stale. You might also consider
    “refreshing” DNS by making a change that would force your DNS records to get

    Good luck!

    Version: GnuPG v1.4.6 (MingW32)


  26. Premnath

    Dear Leo,
    Even though i’m able to receive my mail, i am not able to compose them.it says tat the id doesnt exists , though it is present..
    Wat shall i do,,
    [Email Address Removed]

  27. RHuey

    I have read your article. Thank you very much for the helpful information. I have a particular question: We are residing in Spain and are using a Spanish keyboard. All has been fine up until recently when I would attempt to register at particular websites and when I entered my e-mail address I would receive a message indicating “invalid e-mail address”, and displaying what I had typed as “**************”. This would even occur at sites I was already registered at. I do use RoboForm to login to sites. I would then change the keyboard to English (United States) and attempt it again (and at different times and days) but the same. Even when I send e-mail out I open what I have sent and notice it indicates:
    “Roberta Huey wrote:” not displaying my e-mail address at all. Now this does not occur every time but frequently enough. I would truly appreciate any additional information you can offer. Thank you very much.

    RHuey (PS – it even occurred while trying to send you this comment: “Comment Submission Error. Your comment submission failed for the following reasons: Name and email address are required.” etc., when I had already input my email address…. (H-e-l-p!)

  28. John Paul

    mine isn’t a question so much as an answer, I discovered that hotmail filters out any email with the letters XXX in the email after much frustration, it was a code I was using in my address book but after removing all references to those letters it finally went through…

  29. kathy LaForce

    I BOUNCED (Yahoo Mail) someone who is harrassing me- I did not not want to e-mail with anymore. I bounced his most recent e-mail. Somehow, my whole “sent” mailbox folder sent to him for 48 hours until I found out that a new “Rule” had been set to send him- ALL my sent mails. How could this happen? He is now sending threatening messages to family and friends as he now has many of their addresses. Help!

  30. Jesse Robinson

    I keep having users come up with this error at random times:

    MailEnable: Message could not be delivered to some recipients.
    The following recipient(s) could not be reached:

    Recipient: [SMTP:[email address removed]
    Reason: Remote SMTP Server Returned: –

    Message headers follow:

    Received: from perfectmortgage.com ([]) by builderware.net with MailEnable ESMTP; Fri, 11 Jan 2008 15:07:12 -0500
    content-class: urn:content-classes:message
    MIME-Version: 1.0
    Content-Type: multipart/alternative;
    X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0
    Subject: documents
    Date: Fri, 11 Jan 2008 15:04:27 -0500
    Thread-Topic: documents
    Thread-Index: AchUjSslN2tu91qcQaOT4owbl/we5w==
    From: “Joyce”
    To: [email address removed]
    Cc: [email address removed]
    X-ME-Bayesian: 0.000000

    Any idea what could be causing this?

  31. iBill

    Whenever I am on the road and I use Outlook for emails I cannot send emails. I can recieve emails but I cannot send. The error is always the 550 relaying not allowed to (gmail, yahoo, etc… all of the) So I realize, from your newsletter article that I received, that the problem is due to my location not being able to be authienticated. What is the settings I need to change to fix this?????

  32. Leo A. Notenboom

    Hash: SHA1

    That depends entirely on your ISP/mail provider. You’ll need
    to contact them.


    Version: GnuPG v1.4.7 (MingW32)


  33. Tony Pelusi Jr

    hi, i received this message after sending an email. the recipiant tells me that yahoo sends my message to her spam folder no matter what she does to list me as a safe sender.
    is there anything i can do from my end to open communication?
    thank you

    A message that you sent could not be delivered to one or more of its
    recipients. This is a permanent error. The following address(es) failed:

    SMTP error from remote mail server after initial connection:
    host a.mx.mail.yahoo.com []: 421 4.7.0 [TS02] Messages from temporarily deferred due to user complaints –; see http://postmaster.yahoo.com/421-ts02.html:
    retry timeout exceeded

  34. Leo A. Notenboom

    Hash: SHA1

    It’s not your email address that’s bouncing, this part:

    Messages from temporarily deferred

    indicates to me that it’s your mail serivice that’s blocked.
    In otherwords others using the same mail service have likely
    been sending spam, and as a result that mail service has
    been blocked.

    FWIW appears to be lunarpages web hosting. You
    might try talking to them.


    Version: GnuPG v1.4.7 (MingW32)


  35. erik

    this is the sample sender email:[email address removed]

    error line saying…

    [email address removed]>> unable to connect to″ sample IP Add.

    [email address removed] is the recipient

  36. Alex Watson

    I have had a bounceback with an error not listed on your page:

    : does not like recipient.
    Remote host said: 550 5.1.1 : Recipient address rejected: User unknown in relay recipient table
    Giving up on

    does this mean that the email address i am trying to send to doesn’t exist?



  37. Leo A. Notenboom

    Hash: SHA1

    That’s what I would assume


    Version: GnuPG v1.4.7 (MingW32)


  38. erik

    mr leo, need help!

    this is the sample sender email:[email address removed]

    error line saying…

    [email address removed]>> unable to connect to″ sample IP Add.

    [email address removed] is the recipient



  39. luz

    why my email bounce?i thought everything was ok but suddenly i received it again but not all my emails bounced.pls.help!!the noticed enclosed was message expired for domain at blah…blah..blah..but the one i send email told me that everything is still very good on his part..why all this happen?

  40. Bobbi

    I have a user getting a bounceback on an email address he uses quite frequently. Suddenly he can’t email this guy. Others in my organization can email him, but this guy cannot. He gets a bounce back that the user is unknown. But the user is known since it works for other. Tried using the webmail account for this user and still get the bounce back.

  41. yuriy

    Hi Leo. I’m trying to set my qmail server so it gives me 550 error page when there is no such a user. I’m using virtual manager to manage virtual domains. I have only one domain and every time I’m trying to send message to non existing user qmail-verify accepting anything. I reckon that the problem in .qmail-default which pipes to /usr/local/bin/vdeliver. If I remove .qmail-default from /home/email/[virtual_domain]/ folder email stops working.
    Do you know what I need to change in /home/email/[virtual_domain]/.qmail-default in order 550 error works properly?

    Thanks in advance,

  42. jeff

    Hi Leo, I badly need your help, i have a failed emai delivery, and this is what it say:

    This message was created automatically by mail delivery software.

    A message that you sent could not be delivered to one or more of its
    recipients. This is a permanent error. The following address(es) failed:

    [email edited]
    SMTP error from remote mail server after end of data:
    host mailgate.cybercity.dk [IP edited]: 550 5.7.1 message content rejected

    —— This is a copy of the message, including all the headers. ——

  43. E. Born

    people send me e-mails, I receive them, but the sender gets a “550 not delivered, mailbox unknown”-type message. I sent a message saying “Test” to myself and same thing – got original message and ALSO the message saying it was bounced back. Thanks in advance for any help.

  44. ashish manjrekar

    I have got following message when I am trying to send mail to [Email address removed]. . I am sure that the email Id is in exist and internal mail from bankofindia.com (MMS) are gettting but external mails are not receiving.

    Hi. This is the qmail-send program at yahoo.com.
    I’m afraid I wasn’t able to deliver your message to the following addresses.
    This is a permanent error; I’ve given up. Sorry it didn’t work out.

    [Email address removed]. does not like recipient.
    Remote host said: 550 5.1.1 User unknown
    Giving up on

    — Below this line is a copy of the message.

    Return-Path: [Email address removed].
    Received: (qmail 81659 invoked by uid 60001); 13 Jun 2008 07:34:18 -0000
    DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
    s=s1024; d=yahoo.com;

  45. Leo

    Hash: SHA1

    YOU may think it’s a valid email address, but the mail
    server that is attempting to deliver it does not. There’s
    nothing you can do about that. If you can contact the
    recipient some other way you should verify that you
    absolutely have the right email address, and if you do, then
    he should complain to his ISP.


    Version: GnuPG v1.4.7 (MingW32)


  46. Vrajesh

    I am getting my mail bounced message from my rediffmail id. This is happening with message saying ISP does not like receipient and Remost host says uses not known. Is this possible if sender’s id is blocked by recipient

  47. Leo

    Hash: SHA1

    Unlikely. If the problem is with the host, then it’s more
    likely that the email address part after the “@” is wrong,
    or your mail provider is misconfigured – check with them.


    Version: GnuPG v1.4.7 (MingW32)


  48. SanjayT

    HI sir,
    Can u explain the below error.
    Thanks in advance

    553 sorry, Authentication failed or timed out. Please do get messages first to authenticate yourself.(#4.4.3)

  49. dols


    sometimes, it is the stupidiest thing that causes the problem, and these are mostly not mentioned…

    I had mail.zonnet.nl as outgoing server, and pop.zonnet.nl as incoming.
    After much ado, I remembered that my provider was athome, so I needed to have : mail.home.nl.

    And THAT solved my “553 sorry, relaying denied from your location problem!

    thanks anyway!

  50. chaitanya dandavate

    My problem with rediffmail id


    Hi-This is qmail send program ————

    I have already submitted my problem with rediffmail.com
    I dont want to loose my mail id on rediffmail.com since it is widely circulated

  51. Gems

    Hi Leo,

    Emails I send to hotmail.com are bouncing back. Both from comcast.com, aol(aim) and gmail google’s email website.

    Can you help with the settings on this? Also same is happening with my hotmail.com “live:msn” emails… (Bad Email Address is the message attached) :(

    I associated my gmail address with my MSN live account to stop some of the difficulties that I had with getting email to my younger brother who also has a “Live:msn” hotmail account. His works.
    Can you help with the settings, that are making these emails bounce back?

    I’d need to see the exact error message in bounce.

    – Leo
  52. Matty Smith

    I got these notifications when inviting a number of users to join a Yahoo! Group. In some cases the email addresses in the message were nothing like the one I had sent it to. What is going on here?

    “Sorry, we were unable to deliver your message to the following address.

    Remote host said: 550 5.1.1 http://mail.google.com/support/bin/answer.py?answer=6596 23si10110592gxk.82 [RCPT_TO]”

  53. James Elgan

    Bellsouth E address went to AT&T and they went to YAHOO and now I can’t get a group of contacts E’s to go out. Single E’s go but they too smoetimes don’t make it.This is what I receive back:::

    Hi. This is the qmail-send program at yahoo.com.
    I’m afraid I wasn’t able to deliver your message to the following addresses.
    This is a permanent error; I’ve given up. Sorry it didn’t work out.

  54. Joanne

    The following message to was undeliverable.
    The reason for the problem:
    5.1.0 – Unknown address error 550-‘5.1.1 : Recipient address rejected: User unknown in relay recipient table’
    Does this message mean that my email is being blocked by this person. Is there a way to see if someone is blocking your emails.
    PS I removed the persons email from the message.

    Has nothing to do with a person blocking you – there’s no way to know if a person is blocking you. This error typically results from either a misconfigured mail server (which may resolve itself, or not), or typing in the email address wrong.


  55. Rajeshkanna

    I have an mail application develeped by ASP.NET. IT works fine for different domains, but it displays error as
    ‘Mailbox unavailable. The server response was: Requested action not taken: mailbox unavailable or not local’ for same domain.
    My files hosted in Windows server and mail server is Linux..

  56. kim

    Hi, I am getting the error message – This address no longer accepts mail. Can you help please?

    Thanks in advance

    No, I cannot. The error message pretty much says it all. I’m not sure what you’d expect could be done.

  57. Linda

    How do I resolve this problem?

    Remote host said: 550 SC-001 Mail rejected by Windows Live Hotmail for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation problems. If you are not an email/network admin please contact your E-mail/Internet Service Provider for help. Email/network admins, please visit http://postmaster.live.com for email delivery information and support

  58. deb leahy

    Mine bounces but says it is a permanent error
    that my e/m is blocked by Verizon anti- spam
    system. I am convinced this person has blocked me?

  59. Jim H

    I lost a job opportunity when I could not respond to the job offer within the set time because my ISP, Comcast, was blacklisted for SPAM by Blackhole. I tried every one of my Comcast addresses, my Hotmail and G-mail addresses and all got bounced. When I contacted the blocking agency they told me sorry, there was nothing they could do for me. I called Comcast and they said, “We’re working on it.” Meanwhile, I didn’t get the job. Another time a friend from upstate New York, almost in Canada, sent me a joke with the word Viagra in it. It was a good joke so I replied to tell him so and had some other chit-chat to tell him. I was both bounced and blocked and later found I had been permanently blocked and labeled as a spammer because of the word Viagra in the email and because my reply included his original email. He used an animated emoticon in all his emails and the emoticon had a link at the bottom of the email page for recipients to click on to get free emoticons, too. I had to call his ISP via phone and plead my case to be unblocked. It was a huge hassle and if he wasn’t such a good friend I would have given up. Again, any email from my computer from and email service was blocked. I had another unpleasant experience with another friend whose ISP had installed software called Barracuda to filter SPAM and it was still in learn mode when I got repeated bounces when I tried to email him. It bounced me for everything from keywords to having multiple “To” addresses with maddening frequency. I complained to the ISP probably a dozen and a half times before it stopped. I even emailed the makers of Barracuda and complained. of course, I never heard back from them. Hopefully the company folded.

  60. Sagar


    I am sending emails from my own web server, but some emails are getting bounced. So do you know any solution which will give me a count of bounced emails??

    Your help will be appreciated.


  61. Felicity Moresby

    My emails bounce when I try to send from this hotmail [email address removed] address but not when I send them from outlook express. Also, they don’t bounce when I send them from another hotmail address. This is the message that appears: “This is an automatically generated Delivery Status Notification. Delivery to the following recipients failed. [email address removed]”

  62. Kim Mcgeown

    I receive the message – smtp.secureserver.net said:
    550 #5.1.0 Address rejected
    Does this mean I am blocked?

    Sounds to me like you have it configured improperly. “secureserver.net” seems like an example server name, not a real one. (Of course I could be wrong).


  63. Alex Bryton

    I sent an email and received a response of the Mailor Daemon:
    could it still be, that the destined recipient received my email?
    thanks, Alex

    No. Their mailbox is full and did not have room for your mail. That’s what the message means.


  64. Isabel

    Another reason for emails bouncing is that you are trying to send a large email attachment that your email server can’t handle, or that your recipient’s email server can’t handle due to its size. To get round this I personally recommend using a file transfer service like Tonsho. http://www.tonsho.com
    With them you send an email like normal and their server strips out the large email attachment, your recipient gets sent a link from them including your original message, they click on the link and download the file (can be password protected). You can send emails from their website too. I like their service because emails are still from your usual email address so no-one gets confused. You can start with a free account, although I ended up using them so much I upgraded.

  65. Jaap

    Why do I get the following message?
    The following organization rejected your message: bounce.argewebhosting.nl.
    bounce.argewebhosting.nl # #SMTP#

  66. leila

    Hi, since 2 weeks ago i cant send emails to gmail or yahoo any more using this email [Email address removed.] for gmail/ yahoo emails, some of them will give delivery status emails like below message
    This message was created automatically by mail delivery software.

    A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:

    SMTP error from remote mail server after end of data:
    host gmail-smtp-in.l.google.com []:
    550-5.7.1 [ 1] Our system has detected an unusual rate of
    550-5.7.1 unsolicited mail originating from your IP address. To protect our
    550-5.7.1 users from spam, mail sent from your IP address has been blocked.
    550-5.7.1 Please visit http://www.google.com/mail/help/bulk_mail.html to review
    550 5.7.1 our Bulk Email Senders Guidelines. w30si15839555wfd.58

    but sometimes, i dont get any delivery status email at all.

    i also cannot sent to other emails like other_example@domain.com , it will bounce back with below message
    This message was created automatically by mail delivery software.

    A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:

    SMTP error from remote mail server after RCPT TO::
    host domain.com []: 550-Message rejected because (box1.example.com) []:58613
    550-is blacklisted at rbl.davetha.com see Blocked – see
    550 http://psbl.surriel.com/listing?ip=

    can u pls advise me.thanks alot!

    The mail server or service you are sending your mail through is being blocked for sending spam. Use a different service, or if you’re the one sending spam, stop it.


  67. Archan Oza


    I am Archan Oza Sir I am able to send mail from my id but whome so ever is reply me or sending me mail they are getting below response kindly help me if you can do.

    Hi. This is the qmail-send program at rediffmail.com.
    I’m afraid I wasn’t able to deliver your message to the following addresses.
    This is a permanent error; I’ve given up. Sorry it didn’t work out.

    [email address removed]:
    This message is looping: it already has my Delivered-To line. (#5.4.6)

    That’s a problem with your mail server. You need to contact your email service provider and tell them.


  68. Ross

    Hi Leo

    I get this message when I try to send e-mails:

    The attached message had PERMANENT fatal delivery errors!

    After one or more unsuccessful delivery attempts the attached message has
    been removed from the mail queue on this server. The number and frequency
    of delivery attempts are determined by local configuration parameters.


    How can I resolve this please?


    I don’t know that you can. This is a problem at the recipient’s side, and the message doesn’t indicate what the problem is. Assuming you’re sending to the correct email address I’m not sure what to do next, other than to contact the recipient by some other means.

  69. Shannon

    Hello Leo,

    I read most of this, but I was specifically looking for the 550 SMTP error from remote mail server after RCPT TO host a.mx.myspace.akadns.net 550 SMTP error. This is a permanent error. I’m guessing this person blocked me on myspace, (WAS a “friend”) and I guess I just wanted to verify…I sent the same message from a different e-mail address and as far as I know it hasn’t come back to me. I sure would appreciate your input on this and thank you so much for your time!

    God Speed,


    I don’t believe it’s related to being blocked, but there’s not enough info to say more.


  70. Simbarashe Munhemba

    I have forwarding rules set in CPanel and all the mail that I send to that address is bouncing back with the following message. Trying to get help from my Hosting Service Provider is not helping:

    This message was created automatically by mail delivery software.

    A message that you sent could not be delivered to one or more of its
    recipients. This is a permanent error. The following address(es) failed:

    (ultimately generated from recipient@recipientdomain.co.zw)
    retry time not reached for any host after a long failure period

    —— This is a copy of the message, including all the headers. ——

    Received: from mail-gw0-f50.google.com ([])
    by us101.hostdomain.com with esmtp (Exim 4.69)
    (envelope-from )
    id 1P5LNJ-0002CW-LA
    for recipient@recipientdomain.co.zw; Mon, 11 Oct 2010 12:37:22 -0400
    Received: by gwb19 with SMTP id 19so115755gwb.23
    for ; Mon, 11 Oct 2010 09:36:54 -0700 (PDT)
    DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
    d=gmail.com; s=gamma;
    DomainKey-Signature: a=rsa-sha1; c=nofws;
    d=gmail.com; s=gamma;
    Received: by with SMTP id p2mr2828119anp.52.1286815013838; Mon, 11
    Oct 2010 09:36:53 -0700 (PDT)
    MIME-Version: 1.0
    Received: by with HTTP; Mon, 11 Oct 2010 09:36:33 -0700 (PDT)
    From: Me
    Date: Mon, 11 Oct 2010 18:36:33 +0200
    Subject: Mail Forwarding Check
    To: {removed}@ascendtech.co.zw
    Content-Type: multipart/alternative; boundary=0016e6454a4aca9efe049259f73f
    X-Spam-Status: No, score=
    X-Spam-Flag: NO

    Content-Type: text/plain; charset=ISO-8859-1

    – Show quoted text –
    Content-Type: text/html; charset=ISO-8859-1
    Content-Transfer-Encoding: quoted-printable


    If you receive this message in your yahoo mail it means your domain is=
    now able to send and receive mail as normal. =A0Please do reply to this me=
    ssage from your yahoo account so I can verify.
    Thank you


  71. Emma Ruth Lafiguera

    i cannot receive emails from anybody even to my existing friend. why? i’m already upset with this problem

  72. Aladins Silver

    Hi Leo can you tell me what the message ” 554 maximum message size exceeded” I’ve included the txt from the bounced error message
    Aladins Silver

    Hi. This is the qmail-send program at yahoo.com.
    I’m afraid I wasn’t able to deliver your message to the following addresses.
    This is a permanent error; I’ve given up. Sorry it didn’t work out.

    : failed after I sent the message.
    Remote host said: 554 maximum message size exceeded

    — Below this line is a copy of the message.

    The message you are sending is too large.


  73. Alina

    Hello Leo,

    I have sent an e-mail to a client on outlook without attachments and after 4 hours I received the next warning message:

    The original message was received at Fri, 10 Dec 2010 02:25:50 -0500 from {removed by moderator}.com [removed by moderator]

    —– Transcript of session follows —– … Deferred: 403 4.7.0 authentication failed
    Warning: message still undelivered after 4 hours
    Will keep trying until message is 5 days old

    And until now the contact person did not received it. Could you please explain to me what this means?

    Thank you in advance and kind regards!


    That looks like a mail server configuration issue somewhere along the path to the recipient. I don’t believe it’s anything you have control over – you might need to contact the recipient some other way.


  74. Sandra


    One of my colleagues is getting an error,”Error 553- authentication failed” while sending msgs from outlook 2007. We have a rediffmail pro account. We have checkd and verified incoming & outgoing server settings but it doesnt work.
    Pls help…


    Username and password would be the next thing to check. Use some other way to login (web mail?) to confirm you have the right account and password.


  75. Eric

    getting this message on every replied to email for the above email address. failed after I sent the message.
    Remote host said: 550 5.7.1 Rejected for spam/virus content

    No problem sending new messages, or receiving new messages. only happens when trying to reply.

    any help?

    Not much I can add to that error message actually – it’s pretty clear. For some reason the mail system thinks those messages are spam. There’s no way to determine exactly why.

  76. Ramesh Solanki

    Hi All,

    I m not getting bounce mail notification on inserting/using wrong/invalid
    email ids while sending. It is one of the required facity in Email Server.

    e.g. solanki@ccc.svnit.ac.in (Invalid/wrong Email ID)

    while ramesh@ccc.svnit.ac.in (authenticated Email ID) try to send a mail
    to solanki@ccc.svnit.ac.in
    In this case ramesh@ccc.svnit.ac.in must get the bounce mail notification
    because solanki@ccc.svnit.ac.in is Invalid/wrong Email ID.

    -Ramesh Solanki
    Lan Engg,

    I can only report that bounce messages are not guaranteed. Mostly due to spam, many email providers choose not to generate bounces in all situations.


  77. Glen


    The sender domain is getting a return mail with the below error. can you please help me what is this error and what causes this error

    The original message was received at Wed, 6 Apr 2011 19:07:14 +0530
    from static-mum- []

    —– The following addresses had permanent fatal errors —–

    (reason: 554 try again later)

    —– Transcript of session follows —–
    554 5.0.0 Service unavailable

    Glen Sequeira

  78. Mark Jacobs

    @Glenn: The answer to your question is found in your question itself. (reason: 554 try again later). It’s a problem on another server and the solution is to, believe it or not, Try again later

  79. Prashanth

    Hi am getting below error message when i send mail to group of email ids from my yahoo mail id

    Error Message is

    Received: (qmail 51922 invoked by uid 60001)

    Can i get sollution.

  80. Mixed girl

    Can you please tell me a little about this error message below. I deleted the recipient’s e-mail address that was within the error message for privacy purposes in this post. Basically does this mean that my address is the one being rejected or is it the one I am sending to that is being rejected?

    >> does not like recipient.
    Remote host said: 550 #5.1.0 Address rejected xxxxx@xxxx.xxx
    Giving up on

    Whatever “xxxxx@xxxx.xxx” is, is being rejected. Likely it’s an invalid or erroneous email address.


  81. Brian

    The following message to was undeliverable.
    The reason for the problem:
    5.3.0 – Other mail system problem 554-‘Message not allowed – [320]’

    This happened for the first time ever today to all my friends with a yahoo account and also a BTInternet account. I tried numerous times and had the same result everytime, I used Outlook Express.
    I contacted my isp and they double checked my e-mail settings everything was okay. I then sent a message to the same adresses from the webmail server and they went through okay. I also tried using my Blackberry and they too went through.
    I tried again, using Outlook Express and again they bounced back, with the same error message. I also tried sending them with my anti virus progamme disabled and still with the same results. E-mails to any other addresses went through as normal.
    Can anybody tell me what might be happening. thank you.

    It sounds like your message is somehow tripping their spam or anti-malware filters.


  82. Brian

    Yes Leo that was exactly what was wrong. I finally realised that the date on my computer was incorrect, it was showing the incorrect month. June instead of May. As soon as I set the correct date, the problem was resolved…..It just took me awhile to notice the error….lol

  83. Pia

    I will tell everyone exactly why you are getting those Error Messages.

    If the Error Code is 550 with other numbers attached, It probably is a bad email address.

    If you know for a fact that the email address is good, it means that your email was detected by a spam filter.

    Something inside of your message is stopping your established friend from receiving it. Most of the time its the use of profanity, especially if its a google or a yahoo extension because their filters are pretty sensitive.

    Another reason is that you sent out a Bulk Email.
    If the ISP sees too many emails coming from one source with the same basic content,all of the transmissions are blocked.

    The good thing is if you open up the bounceback it will tell the problem with the delivery.

    Try sending your friend a blank email. If that one goes through, its the content.

    • Thom

      I send out bulk email (300 +) on a regular basis for my sporting club, with a newsletter attached. I use a special sender program which lets me insert pauses between emails, such as send 10 emails and wait 5 seconds. It is enough of a pause to not look like spam flooding. It pulls the emails from a spreadsheet, so I don’t have to use Outlook or my other emails programs that I normally use for regular emailing.
      It works great.

  84. rajeev

    we are getting following error everytime. failed after I sent the message.
    Remote host said: 554 Transaction Failed Spam Message not queued.

    — Enclosed is a copy of the message. To,

    It’s pretty clear that for some reason that remote mail server thinks your message is spam.


  85. Lucky


    Sometimes my customers send mail to my domain, they immediately receive a NDR as the below.
    Delivery has failed to these recipients or groups:

    A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.

    The following organization rejected your message: [xxx.xxx.xxx.xxx].

    [xxx.xxx.xxx.xxx] # #SMTP#

    I checked the seetings in my Lotus server but no reject found like the error msg said.

    Anybody has ideas?


  86. adrian

    I have just added my email accounts to outlook express Ver 6 on my WinXP system. When i send and email i recieve the following error mssg below. however i have the same email accounts set up on my laptop running MS Outlook and WIN 7 and everything is fine…

    “This message was created automatically by mail delivery software.

    A message that you sent could not be delivered to one or more of its
    recipients. This is a permanent error. The following address(es) failed:

    SMTP error from remote mail server after RCPT TO::
    host mail.net4india.com []: 550-Verification failed for
    550-Unrouteable address
    550 Sender verify failed”

    Looking fwrd to a solution to solve this issue.

    thanks in advance.

  87. santosh dhakal

    many time g=i got this email error.could you please help me to solve this error.
    This is the mail system at host gateway14.websitewelcome.com.

    I’m sorry to have to inform you that your message could not be delivered to
    one or more recipients. It’s attached below.

    For further assistance, please send mail to

    If you do so, please include this problem report. You can delete your own
    text from the attached returned message.

    The mail system

    : host mail.anel.com.tr[] said:
    5.7.1 Message rejected due to content restrictions (in reply to end of

  88. Mark J

    The bounce message says “Message rejected due to content restrictions.” So apparently, there is something in the content of your email message that the receiving Email Server didn’t consider appropriate. The IP is from Turkey, and it’s possible they have certain restrictions on what can be sent or received.

  89. DAvid Arumugam

    I created a distribution list consisting of 50++ emails and sent out an email, Received NDM from 20 odd users , however When one of the recipients replied to that particular email , even those who didnt recieve original mail from me, received his reply. Why is that so.
    Both using Exchange server, only difference is, he expanded the group list so it showed all the email addresses while i just sent it without expanding the group.

    • Sending 50++ mails at once can trigger actions because it can looks like spam or exceed certain types of delivery restrictions. Replying to the same list from a different source may not trigger the same spam filters or restrictions. In general sending to 50 people at once on a single mail is a bad idea – you should use mailing list services for something that large, or chunk it up in to smaller segments (10 or less per email).

  90. Tina

    I have an email address that is giving to companies for me and some others to receive certain reports. In turn, I get these emails on my regular email address. I am not receiving emails that go out to a distribution list, but I am receiving the replies to the original email. I can not figure out why this would happen. Any ideas?

  91. Bob Ralston

    Hi, Leo,

    I use “Mail” on my iMac. I have a frequent problem, which doesn’t seem to be addressed in your excellent information above. But I’m sure you’ll be able to help me solve it — or at least tell me whom to contact.

    Here’s the problem. Sometimes I send my email out to MORE THAN ONE PERSON, say to six people, and only ONE of those addresses in incorrect. My mail will be returned to me with a comment like:
    [Return Code 550] sid: 81371q00J1JAsyG01 :: sorry, no mailbox here by that name. (#5.1.1)
    When I click on the attached icon, it shows me my complete message, including ALL the addresses I used. There is NEVER any indication as to WHICH name (or names) had the incorrect email address. I then have to phone each person individually to inquire if they received my email. Usually there will be just ONE person who did not get it.
    Shouldn’t the Mail Delivery System tell me WHICH address was wrong? Is there a way that I can determine this information? THANKS! Bob 1-818-366-3637

  92. ZEKE

    If I send emails to a recipient, get no answer, later talking with the recipient, he
    advised me that he has me blocked, what happened to the emails? I never received
    any notification they were being blocked.

    • Mark Jacobs

      Emails are not normally blockable. What he must have done was to mark your email as spam and have it go to his spam box or directly into his trash folder. You wouldn’t get a notification as that person would technically be receiving the email, but the email is being sent to a folder from which he simply ignores all of the emails (the trash or spam folder).

  93. Bob

    I think I know the answer to this one, but I’ll put it here anyway.
    I’m getting bounce messages like this:

    “Your message wasn’t delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept e-mail from certain senders, or another restriction may be preventing delivery. The following organization rejected your message:”

    Trouble is, the bounce is coming from an e-mail address I didn’t send my e-mail to, and it isn’t mentioned in the rest of the bounce message that contains the original message headers.
    I suspect that the recipient’s system is set up to auto-forward to a personal address, which subsequently rejects the forwarded message. Could I be right, and is it possible to prevent the whole forward / bounce scenario?

  94. GerryR

    There are two other reasons.

    (1) Many people, usually the less-experienced – we all start out that way :), send a reply to no-reply.com or noreply.com or some variation on that which still contains one of those. Look before you send a reply – better still look at the address from which the email came before wasting your time writing a reply. Or click on reply and see what address appears, thus not wasting your time writing a reply which will never go where you had hope it will.

    (2) Some servers will only accept IMAP and not POP3. While I have never run into the reverse case of that problem, i.e. accepting POP3 but not IMAP, it certainly could be a possibility. So my solution to this problem is to have one of my desktop computer use IMAP and the my laptop use POP3. Of course if you don’t have two computers then this is not a viable alternative.

  95. Ivan

    Hi Leo.
    I´m using EXIM with CPANEL and have some troubles to send mail to many domains; not all.
    For example, I can send mail to one domain but when i attach a file (Excel 560 Kb), i receive a mail delivery failed qith the following:

    This message was created automatically by mail delivery software.

    A message that you sent could not be delivered to one or more of its
    recipients. This is a permanent error. The following address(es) failed:

    SMTP error from remote mail server after end of data:
    host mail.domain.com.ar [XXX.XXX.XXX.XXX]:
    550 Action not taken

    Address is ok.
    I can send mails without attach.
    Can you help us?.
    Thanks in advance.

    • No, I’m afraid I cannot. You may need to check with your hosting company, or someone well versed with exim. It may simply be that attachments are not allowed by that recipient, or that the attachments are too large.

    • Mark Jacobs

      This can also happen if the recipient’s mailbox is almost full and the attachment would bring it over quota. Normally the bounce message should tell you that, but the amount of detail bounce messages include varies from provider to provider.

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