How do I mark certain details as old (such as a numbers or addresses) but keep them in Contacts? I have a lot of friends who move countries and jobs frequently. I want to keep their old email and street addresses their Contact card, but not have it appear in the autofill.

Currently, I have created a custom label for phone and email called "old" which let's me keep them. But is there a better way?

Update: It's not just about aesthetics. I have a situation where someone has changed jobs, but I need to keep their old email address so that old emails are still correctly sorted by my smart mailbox. If I just move the email to the notes field, these emails disappear. Am I the only one with this problem?
You could just add the "old" data to the "notes" field at the bottom of the contact. That should stop it from being recognised in the autofill but allow you to keep the info together.

Might not be the desired aesthetic you're looking for. Sorry I don't have a better answer.