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How to Get Email with Attachments Delivered

Question: I have noticed that a number of my emails w/attachments have not been delivered. One ISP actually told me the email was not delivered. I divided it into 2 emails and it seemed to be delivered. Could this be my problem (I receive large files up to 20mb regularly) or a problem with my correspondent’s email account?

There are many reasons emails with attachments fail to be delivered.

Heck, there are many reasons email without attachments might not make it. 🙂

Focusing on just the attachment part of the equation, however, there are a number of potential problems, and I’ll try and touch on a few of them.

We can start by blaming malware.

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Problem #1: Spam filters

Perhaps the single biggest issue is that emailed attachments are the number one vector for malware. The result is that ISPs, mail programs, and mail servers are all extremely suspicious of any and all attachments.

AttachmentYou should be skeptical as well, but you have the advantage of knowing whether or not you can trust the sender and whether or not you’re expecting an attachment. Spam filters don’t have that context.

An attachment is a strike against an email when a recipient’s spam filter analyzes a message. Put another way: if it has an attachment, it’s slightly more likely to be considered spam.

Problem #2: Reputation

Every aspect of an email carries with it a reputation. That includes:

  • The From: address.
  • The domain (i.e. used in the From: address.
  • The email service used to send the email.
  • The specific email server used to send the email.

The reputation of each of those items, and probably a few more I can’t think of, contributes to an email’s probability of being flagged as spam.

Free email services in particular (Hotmail,,, etc.) have a slightly higher chance of being flagged as spam than, say, email from a business domain using a high-quality email-sending service. The reason is simple: those free services have been abused by spammers for years.

The most important thing to realize is that reputation matters. Any item — from your personal email address to the specific server your email service happens to use — can be considered a strike against you if that item has a bad reputation for having sent spam in the past.

Problem #3: Explicit attachment blockers

For the very same reason mail systems consider attachments risky, many email programs now come pre-configured to block access to some or all attachments, and many email systems — most notably corporate systems — often do the same.

The recipient must somehow indicate which attachments are accepted. Depending on their email program or system, this may be something that they can configure by file type (allow “.jpg” attachments, but not “.exe”), by sender (usually by adding the sender’s email address to an address book or contact list), or globally.

Problem #4: Size matters

Large files have always been a problem for email, and ISPs regularly disallow emails that exceed a certain size. Attachments are often the reason, since they quickly add heft to any email message.

The problem is that even though “a certain size” might be getting larger over time as the internet and its technologies continue to improve and grow, it also varies from ISP to ISP. If your ISP allows you to send a large file, it doesn’t guarantee that your recipient’s ISP will allow him to receive it.

Larger files are an issue because of the time it takes to send them and the disk space required to hold them. Unlike simply copying a file from one machine to another, where only two machines are impacted, an email travels across several servers, and each of those has to have the resources to handle it without adversely impacting other email deliveries.

Solution #1: Stack the deck in your favor

It’s impossible to guarantee that an email — with or without attachments — will be delivered1, but you can stack the deck in your favor.

  • To the extent you can, send from email domains and services with a good reputation.
  • Send smaller attachments, as you have, by sending multiple attachments in separate emails rather than together.
  • Ask your recipients to do what they can on their end to ensure that your email is as trusted as it can be.

You might get lucky, and things might improve.

Solution #2: Don’t send attachments

Honestly, this is the real solution: don’t send files as attachments at all. Instead, use a cloud storage service like Dropbox, OneDrive, Google Drive, or others.

The process is fairly simple:

  • Upload your file or files to your cloud storage provider.
  • Get a sharing link2 from that provider (usually by right-clicking on the file or folder in that provider’s interface).
  • Include that link in the email you send to your intended audience, rather than including the actual file(s).
  • Your recipient can then download the file as needed.

Your email will sidestep some of the issues I’ve identified above, will probably be delivered more quickly, and will have a greater probability of making it to your recipient. It’s still not guaranteed, but you’ll have stacked the deck in your favor even further.

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Footnotes & References

1: To be fair, the system is amazingly resilient, and most email is delivered, and even delivered quickly.

2: Generally, this is a public link that anyone can view, but if you and your recipient both use the same cloud storage provider, you can often restrict who is allowed to view the uploaded file.

14 comments on “How to Get Email with Attachments Delivered”

  1. Sending files using a file splitter or (in the case of PDF file, breaking them into multiple files is fairly good solution, all else being equal. The downside I have experiences with file splitter programs is that some require the recipient to have the same program to convert the multiple files into one file (sometimes you want the recipient to be able to view the file as one, not as multiple files. I suspect Leo is getting to the next suggestion in his follow up article: Use a free online file storage for the file then share it with as many people as you want. Your mileage may vary with the storage service when it comes to how you share, how many people you can share with at one time and the amount of time it takes to upload the file to the storage service.

  2. I do a little bit of coding, and if I want to send someone an .exe, it can be a nightmare.
    In one case I zipped it, then changed the file extension to .jpg and told them to change it back. Luckily they had the knowledge to do so.

    • Alas nowadays (2019) many email programmes can actually see through that subterfuge and so they still block your email.

      Alas… and as they say, life’s a bitch… then you die.

  3. The problem (unchanged, as of this morning) is that of my email correspondents, ONE of them is affected thus: His messages containing an “attached file” are stripped of the file, even though the INBOX lineup of messages still shows the Paper Clip icon. Why does AT&T/Yahoo Mail do this? No other correspondent is so affected.

  4. I don’t know if this is still the case because I haven’t sent a .exe file in years but Google blocked emails with a .exe extension. It also blocked them if they were in a .zip file. I got around this by sending them in a .rar file. I’ve now switched to sending DropBox or OneDrive links to download the files.

  5. My early introduction to emailing was in the business world – sending and receiving attachments by email. As a result I don’t share the paranoia of some people in relation to attachments.

    But of course the same paranoia exists in relation to clicking links, so Dropbox, OneDrive, Google Drive, or other links to cloud storage still scares some recipients.

    • It’s not necessarily paranoia if people are really out to get you :-) . But seriously, it’s best to err on the side of caution when it comes to email attachments and links. There really are people out to get you, or at least, get your money.

  6. I have sent six e mails with two attachments, both photos. the recipient continues to say that there is no attachment but I have sent it to others including my own secondary e mail address and the attachments have all been received. what can I do

  7. I have photos or attachments to my messages and they have always been delivered. However, not for 2 days. I don’t use iMessage since my children do not have Apple devices. What can I do to message small attachments?


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