I googled out quite a few but all are at best alpha versions, so it seems I will have to try an code one. Instead of coding one from scratch I would like to build on existing implementation, but a good one.
Any suggestions?
SMTP server - I've used Simple SMTP in conjunction with mailparser. IMHO, these are the best tools on the Internet for building SMTP servers in Node.js.
UPDATE: Simple SMTP has been deprecated. Use SMTP server instead (the successor of the Simple SMTP module).
Haraka: https://github.com/baudehlo/Haraka
Is a full featured mail server in node.js - should do everything that you need.