Delete Cached Email Addresses (Outlook)
If you have trouble sending to a saved email address in Outlook (To: Field automatically populates addresses) try removing the address from the cache and re-populating the address. Use the steps below to delete the address.
To delete a single person's cached email address:
Start typing the person's name in the 'To' field
Click the 'X' to the right of their address
Type in the address manually and proceed normally
To delete the entire cached address book:
Close Outlook completely
Open up your hard drive and click on Users->"YourUserName"->AppData*
Navigate through Local->Microsoft->Outlook->Roamcache
Find every Stream_Autocomplete .DAT files and delete them
Restart Outlook
Click on File->Account Settings->Download Address Book
AppData is a hidden folder, so you will need to hit F10->Tools->View and find and check the "Show hidden files and folders" radio button.