Receiving Multiple Copies of E-Mail

Hello Vern,

-Can you recall when this problem may have started (ie. at a particular OS update?)
-Do you have multiple mail accounts?
-In Mail preferences do you have any Rules setup?

If we can't find what is causing the problem you might consider this Mail.app script. One of it's functions is finding and allowing you to easily eliminate duplicate messages:
http://www.macupdate.com/info.php/id/9178#descContainer_link

Hi, I had this problem, or a variation of it anyway. In my case it was not that I was "receiving" the emails, but somehow they were being copied. I know there were times where I would move a group of emails to a folder (on my mac) by control click > move to > [selected folder] There were times that I would swear that I selected move to but they would not go anywhere, I later discovered that the the messages were being copied by going to Mail <Edit> and seeing that it said "undo copy messages" The other thing that I have not substantiated, but I suspect may have copied messages was when I would change a rule's "move to" destination mailbox, and applied the change.

I hope you find answers for your particular problem but in the mean time, I can recommend some Mail scripts from "Andreas Amann's Freeware", one of which easily found the duplicate messages and moved them to one location. You can find them here: http://homepage.mac.com/aamann/
--
GL,
Kevin

Have you set your mail client to save messages on the server and/or delete them from the server when you've downloaded them?

It sounds like the mail client is getting lost as to which messages have been downloaded already and which are new. The simplest way to fix it is to just delete them off the server when you've downloaded them to your local machine.

The other thing to check is how often your mail client is checking the mail server. If you have it set to a very short interval (e.g. 1 minute) and you have sufficient mail that it takes more than that time to download your messages, it's possible that the mail client is initiating a second connection before the first has finished (I know of at least one mail client that suffers from this). The solution here is to turn off the mail schedule and manually download mail, then turn the schedule back on (maybe at a lower frequency) to continue receiving mail.

I have created many Rules

Look for any rules that move or copy messages to an Inbox. That would cause the rules to be evaluated again... and again...

Are you sure? An account-specific Inbox won't appear as Inbox in the rule, but as <AccountName> instead. The only way to identify it as an Inbox is by looking at the icon, rather than the name...