I've noticed my server bogged down quite frequently lately... and in looking
at my maillog I have noticed that the server is being flooded once in a
while, where many new messages are coming in from the same host.
How can I control this? Is there some setting, similar to MAXRCPT, that
controls how many connections I can accept from a particular host?
There's MAXPERIP which controls the maximum number of connections from the
same IP address. It defaults to 4 connections.