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.