This documentation is for Dovecot v1.x, see wiki2 for v2.x documentation.

Listening on additional ports

Here's a little trick to get servers to listen on additional ports. This can be used for SMTP as well or any other protocol.

with Linux

This requires netfilter compiled into the kernel or loaded as module and the user-space iptables command:

iptables -v -t nat -A PREROUTING -p tcp -j REDIRECT --dport 109 --to-ports 110