These failed authentication attempts are brute-force attack on your SMTP server. We hope your SMTP passwords are strong,
otherwise spammers may succeed and SPAM may go through your server causing it to get blacklisted.
Needless to say, these attacks abuse your server resources - bandwidth, CPU, memory and free disk space (SMTP logs may grow enormously).
allows you to protect your SMTP server from brute-force attacks.
RdpGuard works with any SMTP Server software.
It monitors SMTP port on your server and detects failed login attempts.
If the number of failed login attempts from a single IP address reaches a set limit (three by default),
the attacker's IP address will be blocked.
For Windows Server 2003, Vista, 7, 8, 10, 2008, 2012, 2016