Is there a limit on the size of individual e-mail messages?
Our e-mail servers allow incoming and outgoing messages up to 40 MB in size, including any attachments. However, there are other limitations that make it a good idea to keep them below 7 MB.
On this page:
- Recommended sizes
- Encoded attachments are larger than you think
- Sending files by e-mail has other potential problems
- How to avoid the problem
You should probably make sure your e-mail message attachments are less than 7 MB. That’s because any message you send goes through both our mail servers and the recipient’s mail servers, and it’s common for other mail servers to reject any message larger than 7 MB.
For example, if you send a 15 MB message to an address ending with comcast.net or earthlink.net, our e-mail servers will accept the message from your mail program, then try to deliver the message to Comcast or EarthLink. However, the mail servers at Comcast or EarthLink will reject it because it’s over 7 MB, and it will be returned to you as "undeliverable".
Note that 7 MB is just a recommendation. Some people you write to may be using mail servers with even smaller limits. For example, juno.com rejects mail over 2 MB in size, and netzero.net rejects messages over 5 MB.
Encoded attachments are larger than you think
If you’re familiar with other mail services, you might know that many of them claim to accept messages up to 10 MB. If so, you’re probably wondering why we used the number "7 MB" above.
Here’s why: when you send a message with attachments, your mail program usually converts the attachments with "Base64 encoding" so they can be safely sent through e-mail. However, this has the effect of making them 33% larger than their original size: for example, a 7 MB file is actually almost 10 MB when encoded.
Keeping the size of any attachments below 7 MB makes sure that the actual message the other ISP receives is smaller than 10 MB.
Our Webmail system has the same 40 MB size limit as any other mail program.
However, uploading large attachments with Webmail on a slow connection can take a while, which may cause problems in some Web browsers such as "timeout" errors. (This problem is a limitation of all Webmail systems, not just ours.)
If you have timeout problems sending large attachments with Webmail, we recommend using a mail program on your own computer, such as Outlook or Thunderbird.
Sending files by e-mail has other potential problems
In addition to the size problems, keep in mind that many businesses (and even some ISPs) now reject different kinds of attachments in an effort to stop viruses. For example, some businesses simply reject all
How to avoid the problem
For all the reasons mentioned above, sending files by e-mail can be difficult. Fortunately, the World Wide Web has created a much simpler way for you to make files available to other people: just upload the file you want to share onto your Web site.
For example, if you wanted to share a file named clientwork.zip, simply upload it to your Web site, then send the recipients a normal text e-mail message telling them to click on this link:
When a recipient clicks it, the file will download in his or her Web browser.
Nobody else will be able to download the file unless they know the exact file name. For added security, you could name the file something more obscure, like clientwork757813.zip, and make the link:
If the file contents are important and you need even more security, you may wish to put the file in a protected directory.