[Dovecot] setting up multiple listeners

Hello,

I'm using Dovecot v2 and am atempting to get webmail going. I'm trying to set up imap so that port 993 only is listening on the external interface, for both ipv4 and ipv6, but that on localhost only again for ipv4 and ipv6 unencrypted port 143 is active. I've tried various combinations but keep getting an error invalid number. I've googled and not come up with the missing point.

Thanks. Dave.