UnicornCloud · Email Hosting
We use some blacklists cause they really help us in not getting spam. We use the following DNS lists:
Other things blocked on the SMTP port (25)
- People who use localhost in EHLO command
- People who use IP addresses in EHLO command
- People who impersonate Google, Yahoo or Sohu in EHLO command
- Known ADSL hostnames
We use fail2ban to monitor SSH, Dovecot and Postfix logins. If you try to authenticate with a wrong password more than 3 times in a row in 5min, you will get banned for 4h.
If you get a message you are blocked because one of the blacklists or the other shit, stop using port 25?!