I know I continually promised that 0.8.5 will be the "hard to configure but working SMTP/POP3 servers". Well, sorry... I've checked in a nifty little utility called bin/mkmailserver Unfortunately, there's no documentation yet, so here's a rough explanation on how to use it:
use bin/mkmailserver create <smtp port> <pop3 port>
And you'll have a mail.spl which always answers "I don't know what you're talking about".
To add support for a domain, run
bin/mkmailserver domain <smtp name> <pop3 name> <root dir>
What this means is that if you want to have a server that handles mail for "example.com", but when pulling it via POP3 you just want to specify the local part, use
bin/mkmailserver domain example.com '' <some directory>
The directory should exist and be empty, BTW.
Now you have a user-less domain -- so, it will still answer "I don't know who that user is, sorry". Add a user using
bin/mkmailserver <pop3 domain> <user> <password>
Suppose that I want to add glyph to the POP3 domain above, I'll run
bin/mkmailserver '' glyph s3kr1t
Now, connecting to the SMTP server and sending mail to email@example.com, it will be saved in the directory. If glyph then conencts to the POP3 server and authenticates (via APOP only!) with "s3kr1t", then he'll be able to retrieve that mail.