There has been a lot of problem of IP Blacklisting in an ISP Network resulting in page not opening and other problems. Out of several other cases, one of the most important cause is the use of unsecured SMTP port – TCP 25! Thus it’s a highly recommended action to block smtp spammers so safeguard your network from spammers & reduce chances of IP Blacklisting.
Mostly this activity can be done in any good quality firewall or router and we can easily block smtp spammers using some specific rule set. In this post I’m going to discuss how to block smtp spammers in Mikrotik Router OS. I’m sharing the code snippet which has been performed on the current ROS 6.38.5 and is successfully implemented & tested !