Hi I ran a PBEM some years ago, it went quite well for a while. However I ran out of time to GM, so it disbanded.
I used a combination of emails and web page, emails had PC specific type info, Web page contained campaign setting and house rules.
For combat, players would nominate their actions if attacked, eg. while on the dark plains, my character will attack with 50% if not outnumbered, otherwise try to flee. So I could resolve encounters without having to stop too much.
Overall it worked ok as everyone could work on the game whenever between turns that varied from twice a day to around once a week.