I mistyped an email address, and now every time I start typing an address with a similar name, the bad address pops up in my address list. How do I get rid of it?
Email software and webmail clients tend to keep a local cache of email addresses they have seen. When you type in an email address in a new email (or reply or forward) and it automatically shows you the emails it thinks you could be trying to type, some of that is coming out of that local cache. If someone changes their name, though, or you type an address incorrectly once or something like that, then it can end up getting stuck in that cache as well and keep reappearing.
To remove an email address from your local cache, you can do the following:
Removing Previous Recipients in Outlook
Click the New button to open a new message.
Type the first few characters of the cached name into the field to cause the incorrect address to appear below as a suggestion.
Hover over the address and press the X that appears next to it to remove it from the cache.