Hello :) Normally I permit only port 80 incoming to our webservers, but since each webserver also sends out booking-complete confirmation emails, I would like to also enable incoming port 25 for those remote mail servers who 'call back' to check that the envelope sender / HELO address is truly a reachable mail server. I don't particularly want to leave port 25 simply open, but only for those hosts with whom an outgoing port 25 connection is already established with. Is this possible? Cheers, Gavin.
