I found a Plesk 8.3 server running RHEL 4 last month that was presenting errors when users attempted to send e-mail via SquirrelMail: ERROR: Email delivery error Server replied: 127 Can't execute command '/usr/sbin/sendmail -i -t -email@example.com'. The error was appearing because safe_mode was enabled and SquirrelMail was unable to drop e-mails into /usr/sbin/squirrelmail. After disabling safe_mode on the server, the users were able to send e-mails via SquirrelMail.
I’ve used this extremely basic procmail configuration a million times, and it’s a great start for any server configuration. It passes e-mails through spamassassin (if they’re smaller than 256KB) and then filters any e-mail marked as spam to /dev/null: LOGFILE=/var/log/procmail.log DROPPRIVS=yes</p> <p>:0fw | /usr/bin/spamc</p> <p>:0 * ^X-Spam-Status: Yes /dev/null Of course, you can make this much more complicated with some additional customization.
If you see a large mail queue and your system’s I/O is increasing, you may find messages like these in your syslog: Losing q5/qfg9N5EwE3004499: savemail panic<br /> SYSERR(root): savemail: cannot save rejected email anywhere In this situation, there’s some reason why sendmail cannot deliver e-mail to the postmaster address. There’s a few issues that can create this problem: Missing postmaster alias in /etc/aliases Hard disk is full The mail spool for the postmaster has the wrong ownership The mbox file for the postmaster is over 2GB and procmail can’t deliver the e-mail First, correct the situation that is preventing sendmail from delivering the e-mail to the postmaster user.