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running sendmail on a different port other than port 25

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Rajeev Shukla
Honored Contributor

running sendmail on a different port other than port 25


Has anyone tried running sendmail and another messaging server on a same server.
Like running sendmail on different port (other than port 25) and running say netscape messaging server on the same server on port 25.
Does the configuration work perfect?

Gordon Morrison
Trusted Contributor

Re: running sendmail on a different port other than port 25

I don't know what netscape messaging server is, but if it isn't for email, I'd think long & hard before configuring it to use port 25. If it is for email, why do you want sendmail as well?
Port 25 is by convention reserved for use by mail agents. If on a server, you tell sendmail to use a different port, and have something else using port 25, make sure that every other node on your network knows about it. Seems like more trouble than it's worth. Just use a different port for the netscape messaging server.
What does this button do?
Honored Contributor

Re: running sendmail on a different port other than port 25

First create another copy of for this testing purpose, called In the file, look for a option called
DaemonPortOptions=Port (should be remarked by default), change it to

Then start the sendmail with this .......

#/usr/lib/sendmail -C -bd

Then, double check by running netstat -t to see all the LISTENING port,
and you should be able to see port 4321 is LISTENNING.

You can try do a telnet to the port 4321 by telnet localhost 4321, and you
should get the prompt that you sendmail is running on that port. Note
that, what ever yo do on it wouldn't affect the current that running on
port 25.