If you are having trouble sending some attachments, and you are getting a message saying the attachment is too large, you may the following error message window

If that is the case, please do the following: 

1. Compose the email that you want to send to the recipient, just like you tried before, except DO NOT attach any attachments to the email (yet).
2. Click the Send Registered RMail Outlook Button. 
   
   
3. Check the box next to “Large File Transfer (LargeMail)
4. Click the “Add Files” button.
5. Now select the attachment(s) you want to add.
6. When ready, click the “Send” button to send out the email.