yeah that sounds great! i think the one site i recall doing this acted as a fancy email forwarder and header exchanger; allowed the user to create N aliases, and it would forward them all to the users email. then a user could reply and the server would basically grab the body and convert the outbound headers to match the alias (i can never remember the website anymore though- and it lacked open sourceness or i'd have self hosted that if i could)
many iterations is the way to go - im one who always favors options and tinkering (and sometimes with minimal reading; extra challenge mode) - wont be for a month before i can attempt the self hosting bit but i do plan to try it (so my feedback will be very delayed)
thanks for doin all the hard work good luck and dont burn out!