This tutorial will guide you through installing SSMTP on CentOS 5.6
SSMTP is an extremely simple MTA to get mail off the system to a mail hub. It contains no suid-binaries or other dangerous things – no mail spool to poke around in, and no daemons running in the background. Mail is simply forwarded to the configured mailhost. Extremely easy configuration. WARNING: the above is all it does; it does not receive mail, expand aliases or manage a queue.
Firstly lets install the EPEL repository as SSMTP is not native to CentOS 5.6 base installations.
Install the EPEL i386 YUM Repository
# rpm -Uvh http://download.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm
Remove Sendmail as the binaries can conflict.
# yum remove sendmail
Now install SSMTP
# yum install ssmtp
SSMTP is now installed and all that is let is to configure it.
For a really basic installation uncomment and replace with your mailserver and domain details mailhub and RewriteDomain
# cp /etc/ssmtp/ssmtp.conf /etc/ssmtp/ssmtp.conf.orig
# vi /etc/ssmtp/ssmtp.conf
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
# # /etc/ssmtp.conf -- a config file for sSMTP sendmail. # # See the ssmtp.conf(5) man page for a more verbose explanation of the # available options. # # The person who gets all mail for userids < 500 # Make this empty to disable rewriting. root=postmaster # The place where the mail goes. The actual machine name is required # no MX records are consulted. Commonly mailhosts are named mail.domain.com # The example will fit if you are in domain.com and your mailhub is so named. mailhub=mail.how2centos.com # Example for SMTP port number 2525 # mailhub=mail.your.domain:2525 # Example for SMTP port number 25 (Standard/RFC) # mailhub=mail.your.domain # Example for SSL encrypted connection # mailhub=mail.your.domain:465 # Where will the mail seem to come from? RewriteDomain=how2centos.com # The full hostname #Hostname= # Set this to never rewrite the "From:" line (unless not given) and to # use that address in the "from line" of the envelope. #FromLineOverride=YES # Use SSL/TLS to send secure messages to server. #UseTLS=YES # Use SSL/TLS certificate to authenticate against smtp host. #UseTLSCert=YES # Use this RSA certificate. #TLSCert=/etc/pki/tls/private/ssmtp.pem # Get enhanced (*really* enhanced) debugging information in the logs # If you want to have debugging of the config file parsing, move this option # to the top of the config file and uncomment #Debug=YES