Maximum Email Message Sizes
From SWCP Support Wiki
How big is too big?
We get this question a couple times per week: "What is the biggest message I can send through the SWCP mail server?" The question usually comes after someone has received a bounce message saying their message was too large. SWCP has a fairly large maximimum message size. The problem is usually caused by the receiving server having a smaller limitation on incoming messages.
The table below lists the known maximum message sizes for some popular ISPs. A couple things to remember:
- When you email a data file (document, picture, video), the file has to be encoded to a format which all mail servers can accept. This encoding increases the file size by about 30%. So if the size limit is 20MB, you probably need to keep the original file size below 15MB to ensure it goes through.
- If you are sending audio, video, or pictures, the encoding original encoding of the file can make a huge difference in how large it is. WAV files are usually about 10x larger mp3 files. TIFFs are usually many times larger than JPG or PNG. For video, it's almost always better to use a video sharing site like Youtube or Vimeo than to try and slog the files around through email.
- Your message has to be able to fit through the smallest limit in the chain from source to destination. Most messages make it through SWCP's server easily, but if the receiving server has a smaller limit, there is nothing the sending server can do to make the message go through.
File size limits at some ISPs
| ISP | Max Message Size | Last Updated | Reference Link |
|---|---|---|---|
| SWCP | 100 MB | 6/23/11 | https://members.swcp.com/wiki/index.php?title=Maximum_Email_Message_Sizes |
| aol.com (AOL) | 16 MB | 6/23/11 | http://postmaster.aol.com/Postmaster.FAQ.php |
| mac.com (Apple) | 20 MB | 6/23/11 | http://support.apple.com/kb/HT2670?viewlocale=en_US |
| gmail.com (Google) | 25 MB | 6/23/11 | http://mail.google.com/support/bin/answer.py?answer=8770 |
| yahoo.com (Yahoo) | 25 MB | 6/23/11 | http://help.yahoo.com/tutorials/cg/mail/cg_compose4.html |
| hotmail.com (Microsoft) | 10-20 MB | 6/23/11 | No authoritative reference found yet |
| comcast.net (Comcast) | 15 MB | 6/23/11 | http://customer.comcast.com/Pages/Help.aspx |
