The best practices for email attachment size

Written by lee aurelius
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The best practices for email attachment size
The size of attachments that can be sent and received vary with every mail system. (Chad Baker/Photodisc/Getty Images)

Many mail systems limit the total size of attachments allowed for every e-mail. These size limits vary within each mail system. If an e-mail has attachments that exceed the size limit, the email will not be sent. Sending large attachments through e-mail depends on understanding how much can be sent and how much a recipient is allowed to receive.

Attachment Limits on Free Accounts

There are many free e-mail accounts provided by companies with a large Internet presence. These free e-mail accounts include Hotmail, Yahoo! Mail and Gmail. Each free account limits the total attachment size for every e-mail. Hotmail allows a maximum of 10MB to be attached to every e-mail message. Yahoo allows 20MB and Gmail allows 25MB. Attachment sizes should work within each mail system's guidelines. Failure to do so will result in e-mails not being sent.

Encoding of Attachments

Free e-mail accounts go through a process of encoding. This means that adjustments are made to the files so that other mail systems can read them. The result is adds an additional 33 per cent to the original size of the files. Attachment limits provided by free e-mail accounts also include the encoding.


Yahoo Attachment Limit: 20MB

Attachment Size Before Coding on Yahoo: 15MB

Attachment Size After Coding: 20MB

In the above example, Yahoo limits attachments to a total size of 20MB. A file that is 15MB, after coding, is 20MB. In the case of Yahoo accounts, 15MB is the actual attachment limit.

Attachment Limits on Self-Hosting Accounts

Website owners that have accounts with Internet hosting companies also have access to e-mail accounts. These e-mail accounts can be accessed within the cpanel. The cpanel is also known as the control panel and all website additions and adjustments can be made from there.

E-mail accounts through self-hosting companies also have limits on attachments. The size limit varies with each company. Go Daddy has a total attachment limit of 20MB per e-mail, Bluehost has 10MB and Dreamhost has a limit of 40MB.

Understanding Receiving Limits

Even though some mail systems can send larger attachments than others, it isn't the only factor that limits attachment size. Attachment limits depends on how much the recipient can receive.


Gmail send limit: 25MB

Gmail receive limit: 25MB

Hotmail send limit: 10MB

Hotmail receive limit: 10MB

In the above example, a Gmail account sending to a Hotmail account cannot have an attachment size larger than 10MB. Even though a Gmail account can send 25MB, the email is limited by the recipient's ability to receive attachments. On many mail systems, the receiving limit corresponds to the sending limit.

In the above example, a Gmail account could send 25MB in some situations. This depends on the recipient also having a Gmail account or being able to receive 25MB.

Splitting Larger Files

Some files have sizes that exceed what is allowed by a mail system. One way to get around this is by using a program that will split the file (see Resources). The program takes a large file and splits it into several, smaller sizes. This allows a person to send a large file in smaller portions and to attach it on several e-mails. The person receiving the files would then remerge the split files. Before the recipient receives a split file, they need to be informed before hand. If the recipient doesn't have the same file splitting software, they won't be able merge the files back together. Alternatively, the sender can use a compression or zipping program to shrink the file size and send it as an attachment. The recipient would then need to expand the attachment or zipped file.

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