Gmail address auto fills on a new email but does not show in Contact List.

If I type in the first letters of a know email address it auto fills the full Gmail address. But the address is not found in my contact list. I found several contacts like this.
Where are they "hiding?"
Thanks

from Android Forums at AndroidCentral.com - Ask a Question //forums.androidcentral.com/showthread.php?t=804121&goto=newpost
via IFTTT