When I was at UNC for a couple years I sent and received emails from my Gmail account to lots and lots of people I will never see or hear from again.
This was annoying me recently, when I had to ignore lots of obviously irrelevant-to-me-now email addresses. Where was Gmail finding this stuff -- from my old emails?
In a way, yes. The Productivity Portfolio explains that Gmail creates a new Contact record for every email you receive from or send to someone. The workaround is to find the Contact record and delete it.
Very handy to know, particularly for when friends change work addresses.