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?
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.