This has go me so frustrated. I have an eFax account and in Mail.app I set up two folders. One for sent faxes and one for received faxes. I have rules set up so that Mail.app will "copy" the fax (email) to the appropriate folder for future reference. The sent faxes mailbox works flawlessly.
The problem is that my received faxes mailbox keeps propagating multiple copies of the same message. I checked the rule to see if I did something funky, but that's not it. It seems like the older the message, the more copies there are in the folder. So, a fax I just received will only have two copies, but one that I received 6 months ago will have 6 copies!
I am guessing that there is something that is causing Mail.app to run this rule every so often even on messages that I have already received.
To make things even more strange. I just modified the rule so that it applies a color to the received faxes. Now, when I go into my Received Faxes folder, only the original fax has the color whereas the multiple copies of that same fax do not.
Any thoughts?