Submitted by Anonymous on May 6th, 2009
10 MB or less is generally considered a good size limit for email servers. Increasing the limit beyond this can make the server unreliable or vulnerable to attacks for the reasons listed below.
In many cases, because your email client (a program such as Outlook) does not communicate with the server about the size of the file, the whole email including the attachment will be sent, which can take a long time, and then the server will ‘bounce’ the email, sending the whole email back to you along with a message saying the email is too big to send!