Introduced in release: 18.104.22.168
dnsrbl MMP option provides a list of domain names used to perform a DNS Realtime Blackhole List check for incoming POP and IMAP connections. The checks are performed in serial and may significantly impact the time it takes for clients to connect to the proxy. When a connection is rejected, a protocol-appropriate access denied error will be provided unless the connection is over SSL and the
sslconnlimit option is also set, in which case an SSL
user_canceled alert will be sent. If the
messagetrace.activate option is set to
transactlog, then the rejection will be noted in a
co log entry in the store transaction log.