I currently have two servers running with synchronization that I've been very happy with.  However, I'm seeing the following in my logs recently:

May 12 15:45:58 cloud1 dovecot: doveadm(194.165.16.78): Error: doveadm client not compatible with this server (mixed old and new binaries?)

May 13 03:44:31 cloud1 dovecot: doveadm(45.227.254.48): Error: doveadm client not compatible with this server (mixed old and new binaries?)

Since I don't recognize those IPs, the first is out of Panama and the other is Belize, I assume these are hostile attackers trying to exploit something. How can I defend against this?

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