On the other hand, I looked up my name (Corin Cole) and my company domain (heavenmedia.com) and it found my old email address correctly (c.cole).

I haven't used that in quite a while (we all use firstname@ now), but if it was just randomly guessing format, it wouldn't have guessed c.cole, because only one other person has ever used that format of address, and he left the company two years ago.

So while it may be guessing in some cases, it's not the case all the time.