I used the following article to add port 2525 to qmail:
http://wiki.mediatemple.net/w/(dv):Enable_alternate_SMTP_email_port
It was working fine for a while. I could telnet into qmail on port 2525 and get a response but suddenly it just stopped working.
Now when I try to telnet in on port 2525 it just hangs. I can see that xinetd is listening on 2525 and 25 but no joy telnetting in on port 2525. Telnetting in on port 25 works though.

netstat output:
tcp 0 0 0.0.0.0:2525 0.0.0.0:* LISTEN 12253/xinetd
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 12253/xinetd

Any ideas on how to address this or how to troubleshoot?

Are you sure you even need to do that? You've already got 465 and 587 as alt SMTP ports enabled by default.

I enabled it because I often am in locations where the default email ports are blocked.
Its nice to have a nonstandard port to use to send mail.
I have heard that this method (or similar) can create an open relay which I dont want.

I have another issue:
On port 465 I get:

telnet mail.smallgod.net 465
Trying 72.10.34.217...
Connected to mail.smallgod.net.
Escape character is '^]'.
454 TLS no valid RSA private key: error:02001002:system library:fopen:No such file or directory (#4.3.0)
Connection closed by foreign host.

Nevermind I got the SSL issue fixed.
It seems I pasted the private key in vi without it being in insert mode so it began with:
N RSA PRIVATE KEY-----

If you have any thoughts on the alternate smtp port though...
Thanks for your help!

yup, 465 is SSL smtp, and 587 is the submission port which supports STARTTLS

On the port 2525 issue, do you have a firewall setup, and is the port 2525/tcp open?

When I open up the firewall completely it works so That must be it. (doh!)
Thanks!

Glad we could help, and to be a completely shameless author - you know we wrote a book about just this:

http://www.amazon.com/Troubleshooting-L ... 369&sr=8-1