I am trying to get sendmail working to relay mail from within my companies network. I am using Redhat 8. The default configuration won't let me send mail out, but I can reviece it from a POP account I set up on the machine.

I keep getting 'host name lookup failure'.

What does this mean?

Mar 1 20:28:31 midnight sendmail[1516]: h221SUsu001516: from=xxx@xxxx.com, size=317, class=0, nrcpts=1, msgid=<1046568510.1159.8.camel@midnight.sci-local.com>, relay=root@localhost


Mar 1 20:28:31 midnight sendmail[1516]: h221SUsu001516: to=xxx@xxxx.com, ctladdr=xxx@xxxx.com (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30300, relay=[localhost], dsn=4.0.0, stat=Deferred: Name server: [localhost]: host name lookup failure


Mar 1 20:32:18 midnight sendmail[1534]: h221WIT1001534: from=xxxx@xxxxx.com, size=299, class=0, nrcpts=1, msgid=<1046568738.1225.10.camel@midnight.sci-local.com>, relay=root@localhost


Mar 1 20:32:19 midnight sendmail[1534]: h221WIT1001534: to=xxxx@xxxx.com, ctladdr=xxxx@xxxxx.com (0/0), delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=30292, relay=[localhost], dsn=4.0.0, stat=Deferred: Name server: [localhost]: host name lookup failure

Can someone please tell me what's going on and how to fix it. I have never set up a email machine and I am losing my patience.

Does the error message tell you enough or do I need to provide more information?

Regards,
Eric

you're trying to let OTHER computers use this to send mail out? you're using localhost as the relay, which doesn't make much sense really, you should be sending it to the proper hostname e.g mikescomputer, mailserver or whatever the machine is called, and check the entries in /etc/hosts look something similar to:

127.0.0.1 localhost.localdomain localhost
192.168.0.1 simon simon.hcf
192.168.0.2 trevor

shouldn't really be a problem after that. you may have other problems in there, but those error messages should be a simple problem. how are you actually trying to access the server?