If an old, unwanted email address keeps popping up when you compose a new email message, that old address is probably still in your contacts. Follow these steps to fix it.
- While viewing your Inbox, click on "Mail" in the upper left corner (under the SNC logo) and select "Contacts".
- In the search box at the top, start typing the old address or name. Select the name from the autocomplete.
- While viewing that contact record, click the "More" button at the top and select "Delete contact".
That old address will no longer appear in your autocomplete.