sSMTP – a simple and lightweight MTA used to deliver mail from a computer to a mail hub (SMTP server) using Gmail SMTP servers.
Unlike Exim4, it does not receive mail, expand aliases, or manage a queue.
First you need to stop sendmail if it is installed:
service sendmail stop chkconfig sendmail off
Add the CentOS EPEL repository:
Download and install epel-release-6-8.noarch.rpm:
wget http://ftp.astral.ro/mirrors/fedora/pub/epel/6/i386/epel-release-6-8.noarch.rpm rpm -Uvh epel-release-6-8.noarch.rpm yum update
Install and Configure sSMTP
yum instal ssmtp
FromLineOverride=YES firstname.lastname@example.org mailhub=smtp.gmail.com:587 UseTLS=YES UseSTARTTLS=YES AuthUser=username AuthPass=we suggest creating an app password with gmail 2 step authentication.
Change to default MTA
Usually we ave sendmail as the main MTA, we need to change it:
alternatives --config mta