That would be the Email Autocomplete Cache. To disable it:

Click on File and go to Options.
Click on Mail on the left.


Scroll down to the Send Messages section.
Uncheck the box for "Use Auto-Complete List to suggest names when typing in the To, Cc, and Bcc lines"
Click OK.

You can also clear the cache by clicking the "Empty Auto-Complete List" button

That should be it. Hope this helps.

-SW

Sounds like once I do this then there is no autocomplete at all. I would like to be selective as to what goes into it and still have it in use.

As for the option to empty it, I firsrt create an e-mail message and use the BCC option and the autocomplete to accumulate all the names I want to keep. (Hit A then select what I want, then B, C, D,,,) now I move all the names into the body of the e-mail message and send it to myself.

Delete all and repopulate it by opening the s-mail message and moving the named back into the BCC line. When they underscore, then the Autocomplete has the named I want.

Tedious I know but it works...
It would be nice if I had the option to select what goes in in the first place.