Configure sendmail as a relayserver

Change the following lines in /etc/mail/sendmail.mc

define(`SMART_HOST’, `ventoux.r71.nl’)dnl

dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA’)dnl
DAEMON_OPTIONS(`Port=smtp, Name=MTA’)dnl

LOCAL_DOMAIN(`alpedhuez.r71.nl’)dnl

  # m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

Flush deferred messages in sendmail queue

Whenever sendmail has to deliver mails to other hosts which cannot be reached at that time, the messages are kept in the queue and are marked as “Deferred: Connection timed out”. Although the other hosts could be reached again and you want to tell sendmail to flush the mail queue, the command

  # sendmail -q -v

does not really try to reconnect to these hosts and still assumes that the connection timed out. The reason is that the hoststatus is cached, per default for a period of 30 minutes. Using

  # sendmail -OTimeout.hoststatus=0m -q -v

You can re-run the mail queue and force sendmail to reconnect to the hosts. You may want to define an alias for that, say, ‘sendmail-flush-timeouts’.

Default mail queue interval setting

  #  cat /etc/sysconfig/sendmail
      DAEMON=yes
      QUEUE=1h

Test on commandline

telnet yourrelayserver.com 25

helo <hostname>
mail from: name@extrnaldomain.com
rcpt to: user@yourdomain.com
data
mail test
.