How to configure sendmail in AIX

This guide serve as a record on how i configured sendmail in AIX 7.1 to relay mails to my company's exchange.

Get sendmail running first

# lssrc -s sendmail
# ps -aef | grep sendmail
# startsrc -s sendmail -a "-bd -q30m"
# ps -aef | grep sendmail

You should see the following output

root  5704     1   0 11:08:42      -  0:00 sendmail: accepting connections on port 25

Ensure sendmail runs after a reboot. Edit the '/etc/rc.tcpip' file

# vi /etc/rc.tcpip

uncomment the following startup line in ‘/etc/rc.tcpip’

start /usr/lib/sendmail "$src_running" "-bd -q${qpi}"

Get sendmail to use local hosts for name resolution instead of DNS (default) Edit ‘/etc/netsvc.conf’ file

# vi /etc/netsvc.conf

Add the following:

hosts=local

For security purpose, change the permissions on the ‘/etc/netsvc.conf’ file to lock down root only access:

# chmod 600 /etc/netsvc.conf

Add into the ‘/etc/hosts’ file the IP address and hostname of the Exchange server. use telnet to verify network.

# telnet  25

Add the IP and hostname into ‘/etc/hosts’

# vi /etc/hosts

The email daemon requires FQDN, so say your host is "myserver", append "myserver." to your hostname in /etc/hosts. Backup the original ‘/etc/sendmail.cf’ file and edit.

# cp /etc/sendmail.cf /etc/sendmail.cf.

Make the following changes:

# vi /etc/sendmail.cf

For AIX 6.1, i changed the Dw as well. Don't need it in AIX 7.1. Change from:

#DwYourHostName

To:

Dw

Change from:

# "Smart" relay host (may be null)
# Relay host to forward outgoing mail not in the local domain to.
# To forward ALL mail to this relay host, uncomment the appropriate
# rule in ruleset 0, as indicated by the ruleset's comments.
#DSmailer:relayhostname
DS

To:

# "Smart" relay host (may be null)
# Relay host to forward outgoing mail not in the local domain to.
# To forward ALL mail to this relay host, uncomment the appropriate
# rule in ruleset 0, as indicated by the ruleset's comments.
#DSmailer:relayhostname
DS

Now refresh the ‘sendmail’ daemon with the new changes

# refresh –s sendmail

It will take a few minutes for the ‘ps’ process to return:

root  5704     1   0 11:08:42      -  0:00 sendmail: accepting connections on port 25

In the interim period the following will be displayed via ‘ps’:

root  5704     1   0 11:08:42      -  0:00 /usr/lib/sendmail –bd –q30

Test sendmail now.

# echo “test” |sendmail –v yourname@myinbox.com

Enable mail log by adding the following line in syslog.conf.

mail.debug     /var/log/maillog rotate files 6 time 30d compress

Now, create the log file and refresh syslogd.

# touch /var/log/maillog
# refresh -s syslogd