I was exclusively using my A1200 for email until I got a cable line in about 2003. Back then I wasn't bothered about content-rich emails and was just happy to get text-based emails. YAM was my client of choice. I did get my A500 online (using a Motorola 14.4 modem), but only used it for bulletin boards, as opposed to email proper.
Seems like a good project, though, getting the A500 emailing... hmm..