So check this out—if you open Contacts and look around at your cards, you may find some in which an email address, phone number, or what have you is greyed out and has a little “i” next to it.
OK, so you can’t tell that number is in grey since I had to block it. You’ll just have to trust me.
Anyway, if you click that “i,” it’ll show you the email that it pulled the information from, and you can choose to remove the data from the card if it’s not relevant (or keep it permanently).
In my case, though, I’m pretty good at adding contact data if I need to. Because of that, I’ve had a lot of false positives, which really makes me feel yucky on the inside—I don’t like disorganization, you see. So I’ve turned this feature off, and if you want to as well, go to Contacts > Preferences and click on the “General” tab.
Toggle off “Show contacts found in Mail,” and you’re good to go. Of course, your Mac will warn you that it’s about to remove data.
Ahhhh…that feels so much better. Much cleaner. No one adds contact info but me, by gum.