Messages re sent afetr restart

[RICH3]

I have run into an issue where emails are re-sent after the server is restarted. For instance, the server runs for long periods of time without requiring a reboot, often months. I then rebbot the server either for power shutdown or whatever. My client then starts getting calls from clients that they are receiving email from them that they already got. sometimes from weeks or months before. It not all mail just random messages that seem to have been in "limbo"
Any ideas to set me in the right direction would be appreciated.

 

[Davetoo]

Before you reboot next time, check your queues to see if anything is stuck in them.

I'm Certifiable, not cert-ified.
It just means my answers are from experience, not a book.
The poster formerly known as lander215