Sendmail Configuration

• 25 is the port for Mail in Linux, so check whether sendmail / postfix is already configured and running using the following command,
 [root@Linux root]# netstat -antp | grep 25
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      28849/sendmail


·   Check the services running or idle according to the MTA,
[root@castle-hat tmp]# service sendmail status
sendmail (pid  28849) is running...
sm-client (pid  28857) is running...


[root@castle-hat tmp]# service postfix status
master is stopped


·   Check the RPM’s got installed properly
[root@Linux root]# rpm -qa | grep sendmail
sendmail-cf-8.14.4-8.el6.noarch
sendmail-8.14.4-8.el6.x86_64


[root@ Linux root]# rpm -qa m4
m4-1.4.13-5.el6.x86_64


·   Edit the sendmail.mc
Enable the below lines
LOCAL_DOMAIN(`localhost.localdomain')dnl
EXPOSED_USER(`build')dnl  //////makes the mail comes from build user


·  Write it to sendmail.cf
 [root@ Linux root]# m4 sendmail.mc > sendmail.cf


·   Edit the submit.mc file
            Make sure the below lines are uncommented
MASQUERADE_AS(`hat.com')dnl
FEATURE(masquerade_envelope)dnl
MASQUERADE_DOMAIN(`localhost')dnl
MASQUERADE_DOMAIN(`localhost.localdomain')dnl
FEATURE(`msp', `[relay.na.rsa.net]')dnl


·  Write it to the .CF File
[root@ Linux root]# m4 submit.mc > submit.cf


·   Start the senmail service
         [root@ Linux root]# service sendmail start


·    Mail syntax
         [root@castle-hat mail]# mail -s <SUBJECT> <TOUSERID> < MAILSUB