For some reason, I read somewhere here that the 8700 (or just 4.1) could have different icons for different e-mail addresses. Now I can't find any messages on it, and I'm not sure how this feature works (is it different icons on the home screen or just different icons on the messaging app?) or how to get it to work.

Was I just imagining this feature?

I've not heard of that. Perhaps you're referring to the capability to designate specific e-mail addresses as Level 1 messages, so that they play a different sound when they arrive based on your profiles?