[BlueOnyx:08406] Server Security

[Donald Jacques]

I am seeing the following message quite often in my Logwatch reports:  ------------------------------------------------------------------------------------------------

dovecot: pop3-login: Disconnected (auth failed, 1 attempts):
user=<adrian>, method=PLAIN, rip=203.72.50.53, lip=65.39.71.132: 1 Time(s)

dovecot: pop3-login: Disconnected (auth failed, 1 attempts):
user=<advanced>, method=PLAIN, rip=203.72.50.53, lip=65.39.71.130: 1 Time(s)

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I see two ip addresses listed.
The 69.39.71.13x is a recurring attempt -- almost daily now.
Is there a way to block, or blacklist either ip address?
OR is there a setting I need to check?

Don