So, I was searching around for a way to clear the auto complete email addresses that was in my Iphone. I found a method and have done this on my 3G firmware 3.1.2.
The thread also states there is an app w/ bossprefs called ABRecentCleanup but I did not try it. The SSH method was easy though.
Ill advise if my Iphone crashes in the next few days..........
1) Through SSH, copy AddressBook.sqlitedb file to PC
2) With SQLite Database Browser, open AddressBook.sqlitedb
3) Switch to Browse Data tab and select ABRecent from Table dropdown list
4) Select the record to delete and press the Delete Record button at the top right
5) Continue deleting as much as you want and then Save
6) Transfer AddressBook.sqlitedb back to iPhone overwriting original
7) Reboot iPhone