SpeedMail: Running Shoes For Mail.app
While “automated database rebuilding” for your email may sound scary, it really isn’t – especially if you are suffering from the dreaded Mail.app slowdown. This slowdown is usually caused by bloat in the Envelope index, an SQLite database that Mail uses to store practically everything about your mail messages.
While you could simply punch in a short series of Terminal commands, many may wish to have a more convenient (or less scary) method of rebuilding their Envelope index. SpeedMail by Matteo Discardi of 1802 does just this.

When executed, the program provides you with a simple dialog, asking if you want to perform the action. If you select yes, Mail is automatically closed and your index will be rebuilt. While the chances of something going wrong is rather minute, it’s still always a good idea to backup your index before running the program (at least for the first time).
For you power users out there, check out the article from Hawk Wings for the Terminal method to perform the same task. You’ll be amazed at how much faster Mail feels once you run this app. SpeedMail is freeware, but Matteo asks that you make a donation if you find his software useful.

I am going to try this application out. I rarely do testing because I fear a system crash or slow down. You talked me into this by your article. Wish me luck.
http://www.hawkwings.net/2007/03/18/vacuummail-automated-mail-vacuuming-via-launchd/
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im going to try this application. Thanks