I'm hoping that the above title will help other users out there in nix world. Especially those that use sendmail as a simple mail transfer agent to get email out of a lan off a box thats used as a webserver or monitoring machine.
This was all on Debian stable btw. And its an older box which just works so i haven't ever really updated.
I have been using sendmail very happily for a few years now on a number of boxes, and used a very simple config file with only one major change from the Debian default config, that i use my isp's smtp server as the thing that actually sends the emails on. This saves me from having rdns etc....
We had a power issue at the hosting site and found the ups's had run out before power was back, yay for local power company. It even took out ups beside the main server ups as well as a few monitors in the workshop...
Anyways, sendmail stopped working, checking the log files, i got stupid messages about socket wedge's? what the hell, went searching round the net and every thing that was supposed to be in place was in place, and the config files were ok, and nothing had changed from what i had seen. Even did a fsck on the hard drive and came up with no errors.
Wade thru more logfiles, tells me my isp isnt accepting connections for mail transport, do a telnet to mail.isp.com on port 25, everything works fine. Another log entry shows i might have a dsn error. Huh, dns maybe, but no, specifically a dsn error, more hunting, apparently i have issues with my hosts file, but no, everything was as it supposed to be.
After spending 4 hours pulling out what little hair i had left, i said bugger it, and apt-get remove sendmail and everything non critical to do with sendmail with a --purge. Moved all the files in the /etc/mail directory to a new folder and then reinstalled sendmail, and its bits and pieces including rmail. Set my little change up and away it went.
Its working fine now!
Something somewhere go corrupted. I had very little to go on and the error messages just did not add up to what was being described in the various forums etc that i went too. And 90 % of the time, they only got so far and everyone eventually give up on the problem. With very few people giving answers as to what to do and if they did fix it.
I am writing so that this might come up your regular search site and give you a conclusive answer on the problem, if you come across it. I see too many post of problems with no answers. If this helps 1 person, its worth it.
Here is some of the error messages from the log files....
opendaemonsocket: daemon Daemon0: server SMTP socket wedged: exiting
cannot bind: Address already in use
connection timed out; no servers could be reached>, proto=SMTP, daemon=MTA-v4
xdelay=00:00:00, mailer=relay, pri=150857, relay=mail.isp.com [ip.address.here], dsn=5.0.0, stat=Service unavailable
If anyone can elaborate as to what happened or has answers as to how why and what. It would be appreciated....