Copy /etc/xinetd.d/smtp_psa to smtp2_psa
In the new file, REPLACE service smtp WITH service smtp2
Then modify /etc/services and add the smtp2 service (port 26 in this example).
smtp2 26/tcp mail
smtp2 26/udp mail
Then restart xinetd
/etc/init.d/xinetd restart
Check that the new port is now listening
# netstat -plunt |grep :26
That should return something similar to
tcp 0 0 0.0.0.0:26 0.0.0.0:* LISTEN 2345/xinetd
Test connection by telnetting from an outside box to port 26 on the server:
telnet 123.123.123.123 26
how would you tell the senders what port to send to?
I notified all my users via email
The vast majority will have no problem, but some ISPs are starting to block port 25 altogether (comcast for example).
Well, and what you told them? I mean, how can one specify a port in the e-mail adress?
I think you misunderstand. Everything is transparent to the sender…
I tell my clients who have trouble using the default SMTP port (25) to set up their email client’s outbound SMTP server port to 26…