The BMServer log shows multiple DNS lookup failures of the type "Unable to resolve DNS query for <ipadress>.<domain.tld>", when in debug or "Latency threshold for feature "<domain.tld>" exceeded. Feature has been suspended."
This is usually seen in conjunction with mail queues building and/or bmserver crashes.
"Unable to resolve DNS query for <ipadress>.<domain.tld>", when in debug or "Latency threshold for feature "<domain.tld>" exceeded. Feature has been suspended."
A tcpdump on port 53 will also show a high amount of lookup failures
This is most commonly caused by an incorrect entry in Third Party Bad (or Good) Senders.
The resolution is to transfer the domains incorrectly listed in Third Party Bad (or Good) Senders to Local Bad (or Good) Senders and make sure Third Party Bad (and Good) Senders only contains actual realtime DNSBL providers.