How to install and configure sSMTP on CentOS / Fedora / Redhat

sSMTP is alternative to Sendmail.  sSMTP is a send-only sendmail emulator for machines which normally pick their mail up from a centralized mailhub (via pop, imap, nfs mounts or other means). It provides the functionality required for humans and programs to send mail via the standard or /usr/bin/mail user agents. It is used to send mail to external email address after authentication with valid mail account.

Download & Install

# rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-4.noarch.rpm
# yum -y install ssmtp

Now we will edit the ssmtp configuration file. 

# cd /etc/ssmtp
# vim /etc/ssmtp/ssmtp.conf

Here is the custom configuration 

MailHub=mail.techgyaan.org:25          # SMTP server hostname and port
UseTLS=NO                              # Secure connection (SSL/TLS)
FromLineOverride=YES                   # Force the From: line
Hostname=mail.techgyaan.org            # The name of this host
RewriteDomain=mail.techgyaan.org       # The host the mail appears to be coming from
Root=Bala                              # Redirect mail for root@ to postmaster@
AuthUser=bala@techgyaan.org            # Your DreamHost mail account
AuthPass=myemailpassword               # The password for the mail account

Now let’s configure the Aliases

# vim /etc/ssmtp/revaliases 

root:alerts@techgyaan.org:mail.techgyaan.org:25
Postmaster:alerts@techgyaan.org:mail.techgyaan.org:25
Bala:bala@techgyaan.org:mail.techgyaan.org:25

If you would like to change the "From" Display Name, edit the /etc/passwd and modify the user alias

# vim /etc/passwd 

alerts:Alerts:507:507::/home/alerts:/bin/bash
bala:BALA:505:506::/home/bala:/bin/bash
postmaster:POSTMASTER:505:506::/home/postmaster:/bin/bash

Before we start using sSMTP lets stop the sendmail which is default installed on all Linux distribution.Stop sendmail service to start after reboot

# service sendmail stop
# sudo chkconfig --levels 2345 sendmail off

Move or replace the sendmail and then create a symbolic link for sSMTP to sendmail with authentication

# mv /usr/sbin/sendmail /usr/sbin/sendmail.orig
# ln -s /usr/sbin/ssmtp /usr/sbin/sendmail

We all done with the installation and configuration let’s send a test mail to internal & external email address using sSMTP. 

echo "Sending Test mail to external & Internal email address"| mail -s "This is the test message using sSMTP" bala@techgyaan.org bala@gmail.com

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