Please note that file attachments are not included on the emailed alerts of task comments and disucsssions.

This is because it is very complex to do so with regards to the permissions system.

We’ve left it for now because you can easily see the attachments by clicking on the link in the alert that opens the task or discussion

Also on a related note: you cannot email in files via a comment reply

Note that you CAN email files in with a task created by email (read more) just not with a reply to a comment

We’re looking into improving that soon.