Stop your sendmail daemon before deleting /var/spool/mqueue/* files.
sh /sbin/init.d/sendmail stop
*Something* seems to be using your sendmail to continuously queue up more and more emails for sending, and your sendmail cannot deliver them to the destination for some reason.
1.) Check your cron job log: /var/adm/cron/log. Are there any often-repeating cron jobs?
If a cron job is producing any output to the standard output or standard error, the system will attempt to mail the output to the owner of the cron job. Normally this causes the /var/mail directory to grow, but if the cron job emails have been redirected to a remote destination which is unreachable, it will cause the /var/spool/mqueue directory to grow.
2.) If your system is accessible from the Internet and you haven't done anything to protect HP-UX 11.11 system against spammers, the spammers will eventually find your system and use your disk space, CPU time and network bandwidth to spread their junk emails.
The spammer connects to your sendmail, says "Hey, please deliver this message about herbal male enhancement pills to this list of 100 000 email addresses" and disconnects. Many of those addresses may be gathered programmatically from discussion forums and web pages, and a lot of those addresses are old or flat-out incorrect.
Your sendmail doesn't know this and makes multiple attempts to deliver each and every mail to its destination, storing each undeliverable message for about a week before eventually giving up.
This is called "being an open relay" and it's a very bad mail server administration practice. It harms you by letting the spammers consume your network bandwidth, and also harms other people by pushing unwanted junk messages to their systems.
Most email administrators hate junk emails and may report known spam relays to various blacklists. If this happens to you, emails from any server at your site may be rejected by some mail servers, causing problems in your email connectivity. Most blacklist systems will periodically verify whether the problem still exists and will eventually expire the blacklist entry if the mail system is secured, but this can take a while.
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Read your /var/adm/syslog/mail.log to find out where these messages are coming from. If they have been generated on the local system, it is because some process has problems; fix it.
If these troublesome messages have been arriving from an outside source, start improving the security of your sendmail configuration. If your system does not have to receive email from the outside world and you have a firewall, block all access from the Internet to TCP port 25 of your HP-UX server.
MK
MK
