This question is now over 10 years old: ''In the auto-complete of e-mail addresses, old invalid addresses keep appearing in this list that are not in any address book (any more). How can I delete one from the list, or perhaps all?'' It's not mine, and I'm pretty sure the bug is far older than this. You send one email to a person and afterwards their email keeps popping up in suggestions '''even though you didn't save it in collected addresses'''. The only solution offered is an extremely clunky, labour-intensive workaround. It's not the users' fault. When is this absolutely-not-a-feature getting the attention it deserves? The option Collected addresses should not work if it's not selected. Yours in annoyance on a hot and sticky day.