Mail autocomplete is different for search and compose It annoys me that Mail “To” field autocomplete doesn't match that of the search bar.

When I start typing name of a person I've had conversation with in the search bar, I can see their full name along with the address. Clearly, Mail knows about them.



When I hit Compose and start typing in “To” field, I see a tiny loading wheel image appearing on the right for a fraction of second—and then, nothing, no autocomplete, no suggestions. 



The search field looks among all the people you've ever talked to  but the compose form only offers your address book contacts.

Can I change it to work the same way as Search bar, or do I have to add each person in my address book to have them in autocomplete?

I'm using Gmail.
The difference in autocomplete stems from the fact there is no “Mail knows about”. The lookup happens on two different sets of data:


Autocomplete in search happens on the Spotlight index of all received and sent mails in Mail.app’s database (since version 2 of Mail.app).
Autocomplete on compose happens on Mail.app’s potential recipients list, which is a compound of contacts with an email address in Addressbook and a list of previous recipients stored by Mail.app (a list you can see and edit under Window » Previous Recipients).


Notice the difference: search knows about people you have only received mail from, compose does not. Hence different autocomplete results.