Cisco Ironport ESA Attachment Showing As N/A in Message Tracking

This is a known issue which can be fixed by applying a message filter to add the attachment name into the message header. Log in to the CLI of the Ironport device, enter the command "filters", and change to cluster mode if asked. Enter "new" and then copy and paste the following code: -

Add_attachment_header:
If (attachment-filename == "^.+$")
{
Insert-header("X-Attachment-filename", "$filenames");
}
.

Commit the changes by entering the "commit" command.
If you want to view the message filter after it has been applied you can use the "list" command.