I was typing a personal mail to family members and using Gmail's address completion feature to just type a few characters for each recipient when I got to filling in the message body. I looked up and saw a warning about the
To: list. It asked if I really meant to mail PQT, perhaps I really meant PQR? And it was right.
Gmail recognized that I mispicked one of the recipients while using completion, and that I would prefer a relation rather than a friend for this mail. Gmail is smarter than I am.