In cPanel webmail (Horde & SquirrelMail), this attachment limit is 50 MB.
In other webmail programs, attachments are limited to the php_upload size. This was recently updated to 64 MB.
How can I increase my php_upload limit?
This cannot be increased on a shared server. We can only increase this limit on a dedicated server.
When I send an e-mail with an attachment it is not delivered or bounces back why?
The most common reason is the size of the attachment. Aman Corp does not enforce an attachment limit, but if you're sending a 10mb or larger attachment it may fail because it is too much for your Internet Connection.
The server is designed to block some attachment types if they are not zipped up. A few of them being blocked are: .pdf .src .exe. The reason for this is that your mailbox would be flooded every day with viruses if this was not in place. Unfortunately, there is no way to turn this off; your only option is to zip your attachment.
How can I send extremely large files??
Add the file to your site and email the link, instead.
The information needs to be secure.
You can put the files in a password protected directory, and email the link along with the user name and password.