You might not be able to send mails with attachments because of:
- A local antivirus / security application running on your local
computer. It might detect that the attachment is either not permitted or
is infected by a virus. In this case try disabling your application and
resending the attachment;
- The file extension is found in the forbidden extensions list on
the server. An example of this is the .eml extension; In this case try
sending your attachment in a different format.
