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How Long Does Email Delivery Take?

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1. How long does e-mail delivery typically take? What are the most common ranges?

2. How long does it actually take (more or less) for the mailer-daemon at my e-mail host (or whoever) to find the addressee mailbox is full, the addressee is unknown or otherwise undeliverable? (such as address misspelled)

3. Where the addressee data seems valid, how long will the mailer-daemon at my e-mail host (or whoever) keep trying?

Answers to these questions might be of general interest to people frequently replying  to pen pals.

I’m guessing it’s really only the answer to #1 that most people will be interested in, but I’ll hit the other two as well.

People have high expectations of email, and most of the time, those expectations are met.

However, what’s considered “allowed behavior” may surprise you.

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Email delivery speed

Computers are fast, and the internet is fast, so it’s no surprise that most of the time, email is fast. It’s not uncommon for email to be delivered and ready to be read or downloaded in mere seconds of the sender hitting “Send”.

A few minutes is probably more common.

A few hours is quite possible.

Here’s the surprise, though: a few days is also possible, and quite acceptable behavior.

Your email could take seconds, or it could take days. Most of the time, delivery is closer to seconds than days, and we’re typically happy with the time it takes for email to get from point A to point B.

Delays happen

EmailSo, what might tip the scales? What might cause an email to take hours or days to reach a recipient?

There are several possibilities.

SPAM (#1)

Some spam prevention mechanisms cause delays on purpose.

For example, the first time someone emails me directly, my mail server may say, in effect, “I’m too busy for you now; come back later”. This technique — known as greylisting — prevents a fair amount of spam, as many spambots won’t “come back later”; they move on to their next target.

Legitimate mailers, on the other hand, will wait “a while” and try again, at which point the email is accepted. The length of the delay varies quite a bit based on the sending server; I’ve seen it be a few minutes, and I’ve seen it be a few hours.

SPAM (#2)

Mail servers can sometimes be brought to their knees by an incoming flood of spam. The server can’t keep up, and legitimate email can be delayed.

The spam problem is huge, and I believe this is fairly common. I see it from time to time with big email services and with mailing list providers. Email typically makes it through eventually, but with an added delay.

Failures

Hardware breaks. Machines fail. Networks fail. Servers crash.

Then they get repaired.

Mail servers are designed to note that some errors are temporary, so they keep trying until the error gets resolved.

In this case, the delay can be up to five days. You may have seen bounce messages that say, in effect, “I’ve tried for five days and couldn’t get through — I’m giving up.”

Load

Sometimes mail servers are overloaded with legitimate email. This happens from time to time, particularly with mailing list services.

User error or behavior

Email delays can also be our own fault, for several reasons.

  • Occasionally, we compose a message and forget to hit Send. It’s not until we notice and do so that the email gets sent.
  • On occasion, someone might write their email while not connected to the internet. The message isn’t sent until after they make the connection.
  • At the other end, if someone only checks their mail every three days, you might see what looks like a three-day delay.

It’s usually quick, but

As you can see, there are many legitimate reasons email gets delayed. The good news is that if it can be delivered, it typically will be, eventually. The even better news is that “most of the time”, it’s pretty quick.

You just might not be able to count on it. Smile

On mailer-daemons

A “mailer-daemon” is software that runs in the background on mail servers to deliver and otherwise process email.

Mailer-daemons typically process mail very quickly, so decisions on the validity of email, the state of a mailbox, or anything else that can be determined easily by looking is extremely fast — as in less than a couple of seconds, if even that.

How long a mail host will keep trying to deliver an otherwise legitimate email depends on the specific problem that is preventing delivery, the decisions made by the author of the server software, and configuration choices made by the mail server administrator.

Typically, failure will either be immediate (if it’s clear that the problem is something permanent) or within several days (if it’s something that might resolve itself over time).

It’s important also to realize that failure — be it immediate or after a delay — may not generate a bounce or error message in return. In other words, it’s frequently the case that errors happen, but you never know.

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13 comments on “How Long Does Email Delivery Take?”

  1. I enjoy your e-mails.

    I sent an e-mail to a friend – he said he did not get it.

    A couple of weeks later I resent it.
    The friend said he got my new message and then a few hours later got the original message.
    Just like you said – It CAN take some time for e-mail to be delivered.

    Reply
  2. First of all, this is my first time writing on Ask-Leo… (i’m pretty excited XD)

    A question and a comment:

    1.- Is more common for an email to be late due to the crossing from one free e-mail service to another, i mean, is normal or more common, for an e-mail from a GMail user to a Hotmail user to be late or considered as Spam, than if it comes from a user of the same free service?

    I ask this because i’ve heard lots of people saying things like “Hotmail don’t like ro receive mails from GMail accounts” or “This two companies have issues…” And i would like to hear some more technical opinion…

    2.- I’ve Used free Hotmail for more than 10 years, Yahoo! for like 5 years and GMail since it started, E-mail is sometimes a little late, but it’s way better than telephone or SMS services in my country. And it can be free.

    I know people like to think that the email providers are somehow intentionally blocking or delaying each other, but in my experience that’s not the case. Blocks and delays happen most often due to attempts to stop spam, or simple failures, and are not targeted at specific providers.

    -Leo

    Reply
  3. I recently had a very important (time-sensitive) message go astray (to me from someone else), and from viewing headers when it finally arrived it seems it lingered in my email server’s queue for several days before being delivered even though other messages got through. A mystery, but it happens. And these were not “public” email servers in the sense of hotmail etc.

    The moral is, if you are dealing with time-sensitive or otherwise important emails, either request a “read receipt” or specifically ask in the message that receipt be acknowledged, otherwise (short of a reply) you will never know if it went through or not.

    And, if you are on the receiving end, be courteous and respond to the “read receipt” request (if it is legitimate mail) or reply so the sender knows it got to you.

    Occasionally things are lost forever, I have had this happen as well…

    I’d advise not relying on “read receipt”. It’s notoriously ineffective. Some mail programs don’t support it, and most users ignore it even when valid.

    -Leo

    Reply
  4. I understand that there are occasional delays, but my niece recently received an e-mail from me dated from 4 years ago. How is that possible?

    Wow. No idea. Lots of wild speculation (crashed server restored from a 4 year old backup? Random things like that), but nothing really sensible. I’d look at the headers and see if possible where the delay was: Why is some email to me delayed by days?

    Leo
    03-Jan-2011

    Reply
  5. Does it take any longer for an e-mail to be delivered from one country to another?

    Not usually, no.

    Leo
    01-May-2011
    Reply
  6. Ted: International email does not usually take significantly more time , but in some cases it can take longer.

    Reply
  7. As a small business, we recently signed up for Google GMail for business. While it costs $50 a year per account, it sends and receives immediately (and internationally), is really stable and has great spam capture.
    Note: Check your Spam folder occasionally to make sure it has not captured an email that is not spam!
    One more thing: GMail uploads your attachments before you send the email, so when you hit “Send”, it goes immediately.

    Reply
  8. Whenever I get an email from the Mailer Daemon saying the message is delayed, I’ll resend the message. It will almost always, like most email, get delivered instantly. I usually add a line saying why I’m resending it so the recipient won’t wonder why they are getting the email twice.

    Reply
  9. I have been receiving email from someone from Russia have become very good friends with her so when I receive email from her how long does it take and is it probably genuine email coming from Russia as it would be if sending or receiving in the uk. Thank you for your help.

    Reply
    • There is little difference between email to/from Russia or to/from any other country. It normally takes a few minutes, but it may take second or hours.

      Reply
  10. Yes I am too are corresponding with someone in Russia
    They are with G mail and I’m with Optus in Australia
    The e mails usually take just under two hours
    Thanks

    Reply
  11. My sister sent me an email with a photo. She sent it 3 times and I never got any of them. She then texted the photo and I received that promptly and forgot about the email. No joke here, I recently received those 3 emails that were sent 2 years ago. That’s right 2 years ago they were sent, and I just got them now.

    Reply

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