FutureQuest, Inc. FutureQuest, Inc. FutureQuest, Inc.
Knowledgebase: Email
File size limit for email?
Posted on 15 January 2004 01:05 AM

Is there a maximum file size limit for email?

I mailed myself a large file (~30 megs?) from the office and it has not arrived.

I also tried to send an email with an attachment to a co-worker and I received an error message - "exceeded max message length".
The attachment was about 30 MB.


FutureQuest highly recommends using FTP to transfer large files.

For sending and receiving email, FutureQuest allows up to 35 MB for any single message, which translates to approximately 25 MB total for all attachments (depending upon nuances of Base64 encoding) plus the size of the email itself.

(Note: Due to legacy issues, only packages hosted on the Genesis Class servers can send messages over 15 MB. The Server Info page in your CNC will indicate the class of your current server and allow you to request a free upgrade to a Genesis Class server.)

When an attachment is sent via email, it goes through an encoding process to allow the transmission of binary data over email.

As a result of the encoding process, the original size of the attachment will increase substantially. While it is not really feasible to calculate the exact size in advance, you can figure that the Base64 encoding process will increase the attachment size by approximately 35%. This means that a 30 MB attachment may grow to almost 41 MB during transmission (which would cause the email to exceed the allowed limit).

It is also important to note that messages with large attachments which are sent to multiple addresses may be treated as bulk, low-priority messages and shunted to the bulk mail server to prevent mail queue backups. This may mean a delay when sending such emails. Therefore, it is best when sending large emails (over 5MB) to send them to as few recipients as possible.

Also, when sending messages to an external network, it is possible that a large email may exceed the limits set by the receiving network.