Everybody who owns a server face Spamming issues resulting server IP being blacklisted. To overcome this situation, an option is to limit outgoing emails from the dedicated server.
Login to your server’s WHM as root. Access Main >> Server Configuration >> Tweak Settings. Look for “Max hourly emails per domain“. It is the maximum number of emails each domain can send out per hour. By default it is set to unlimited which is a high risk. You can click the Radio Button just below it, limit it to the one you want. Click on Save & you are done. Our shared hosting plans offer 500 emails per domain per hour.
This will limit the emails being sent from email@example.com. But, there are scripts which send emails using firstname.lastname@example.org OR cPaneluser@domain.com. This is possible using scripts in php, perl etc. To overcome this, you need to enable SMTP Authentication. SMTP AUTH as the name says, is a method to send emails using authentication mechanism. Email won’t be sent using a script if it is not authenticated with correct Username & Password.
To enable it, you need to add php mail to disable function in php.ini. Doing this, every user who uses a contact form OR script to send emails, will need to enable SMTP AUTH in the scripts. Contact any of our support representative & they will assist you with enabling it.