CiviCRM Community Forums (archive)

Searched but didn't find anything, and I haven't verified the problem, but have a guess, so maybe will help others: The $mail object passed into the hook appears to know about the attachments, but since Civi moves them from the temporary file used during original parsing, they don't exist anymore at that location.

Calling $mail->generateBody() gives blank attachment sections.

A workaround is to use $result['id'] to get the newly created activity id, and locate the attachments from there.