What is it and how do I clean it up?
If you’re a regular Outlook user, you know that when you compose a new email message, when you start typing in the To: box, Outlook will try to complete the address for you. Here is an example:
This is called autocomplete and normally it’s a big help to keep you from having to dig up an email address. The problem is that you may have an address in the list that is invalid either due to the recipient changing their email address or perhaps you accidentally input an incorrect address.
While there is no easy way to change an address that is in your autocomplete (there are some non-Microsoft applications that do this), you may purge the invalid entry and then input an address that is valid. After that, Outlook will then retain the correct address.
To remove the address, start composing the new email when you see the invalid entry, tap your down arrow on your keyboard until you have it highlighted. Once that is done, tap the delete key on your keyboard. Alternatively, depending on what version of Outlook you are using, you can also click the little X to the right of the invalid entry and that will purge it as well.
For more information on this, including how you can disable this feature of Outlook, visit http://office.microsoft.com/en-us/outlook-help/outlook-completes-the-e-mail-addresses-you-begin-to-type-HA001034792.aspx.