Sam Pointer

When installing Sendmail from the repository packages it is pretty much assumed that you will only be running one instance on a given server. If, like I had to recently, you want to maintain a number of sendmail configurations and process, but want to fit into the Debian rc script scheme, it takes a bit of work.

I’ve created a patch that can be run against the stock /etc/init.d/sendmail script to produce scripts like /etc/init.d/sendmail.mail1 to manage named instances of sendmail. There are a few things you need to know:

• The patched scripts expects to find the configuration for the named instances in /etc/mail/servers/instancename
• The script expects to be called sendmail.instancename
• Along with changing the INSTANCE= variable at the top of the script, be sure to change the comments so that the update-rc.d style daemon registration works if required. A global search and replace is probably your best bet.
• /etc/default/sendmail can be copied to /etc/default/sendmail.instancename and populated, if present or required.
• PID and lock files end up in /var/run/sendmail.instancename. You will need to edit your named instances sendmail.mc/cf to have the PID files created in the correct location. Spools end up in /var/spool/mqueue.instancename

The final piece of configuration required to make this mechanism work is to copy /etc/mail/sendmail.conf to /etc/mail/servers/instancename/sendmail.conf and to modify the MISC_PARMS variable:

MISC_PARMS="-C/etc/mail/servers/INSTANCENAME/sendmail.cf"

Substituting INSTANCENAME as required. This ensures that the correct configuration file is read from.

If you are binding your sendmail instances to different interfaces you might like to also modify the DAEMON_NETIF variable to have the instance watch the correct interface for state changes, if you have DAEMON_NETMODE set to something other than the default “Static”.

Apart from that the patched script does everything that you would expect and the various logged messages reflect the instance name. Managing individual instances then becomes a matter of:

$ sudo service sendmail.mail3 stop
$ sudo service sendmail.mail2 start

Easy as that.

If you want your Sendmail instance to accept mails for a nonsense domain and then discard them completely, here is one way of doing it. Another is to use milters. This is documented to death for Linux and the *BSDs, so I thought I’d write down the steps for getting it working under Solaris 10.

This guide assumes that the main *.cf files have always been built through m4, and that the .mc files in /etc/mail/cf/cf are current.

All steps to be performed as root.

Make a backup of your mail configuration, just in case

cd /etc
cp -pr mail mail.bak

Edit the sendmail.mc file to add the virtusertable feature definition.

cd /etc/mail/cf/cf
vi sendmail.mc
...
DOMAIN(`solaris-generic')dnl
FEATURE(`virtusertable')dnl
define(`confFALLBACK_SMARTHOST', `mailhost$?m.$m$.')dnl
...

Build your new sendmail.cf, setup some configuration files, restart sendmail and ensure the SMF-managed service has been been restarted and is marked “online”.

/usr/ccs/bin/make
cd /etc/mail
cp sendmail.cf sendmail.cf.bak
cp /etc/mail/cf/cf/sendmail.cf .
echo "nowhere.com" >> local-host-names
echo "@nowhere.com:    nobody" >> virtusertable
makemap hash /etc/mail/virtusertable < virtusertable
svcadm restart sendmail
svcs -a | grep -i sendmail

Test that it really works as we think it should. You should also try mailing a “real” deliverable domain if you intend this Sendmail instance to do that for normal mail. (You can paste this whole box straight onto the command line and it’ll work)

mail bob@nowhere.com
TEST
.
mail mary@nowhere.com
TEST
.

Finally, we check the logs to ensure everything is working. The important parts to look for are ‘to=/dev/null’ and ‘mailer=file’. Check your spools, too.

grep -i nowhere.com /var/log/syslog

Jun 11 14:05:59 dev sendmail[4472]: [ID 801593 mail.info] o5BD5xto004472: to=bob@nowhere.com, ctladdr=sam (60005/10), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30103, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (o5BD5xsQ004474 Message accepted for delivery)
Jun 11 14:05:59 dev sendmail[4476]: [ID 801593 mail.info] o5BD5xsQ004474: to=/dev/null, ctladdr= (1/0), delay=00:00:00, xdelay=00:00:00, mailer=*file*, pri=30551, dsn=2.0.0, stat=Sent
Jun 11 14:06:18 dev sendmail[4489]: [ID 801593 mail.info] o5BD6Iem004489: to=mary@nowhere.com, ctladdr=sam (60005/10), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30103, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (o5BD6Iru004490 Message accepted for delivery)
Jun 11 14:06:18 dev sendmail[4491]: [ID 801593 mail.info] o5BD6Iru004490: to=/dev/null, ctladdr= (1/0), delay=00:00:00, xdelay=00:00:00, mailer=*file*, pri=30553, dsn=2.0.0, stat=Sent