Failure to correctly set mail.smtp.localhost in RemoteDelivery leads to mail servers being listed on cbl.abuseat.org and mail being rejected by Spamhaus.
Shortly after the upgrade to 2.3.0 we were listed on the CBL (cbl.abuseat.org)
block list apparently because our mail server sends "localhost" as the
HELO when doing RemoteDelivery.
Attempting to use the <bind> tag to RemoteDelivery as noted on some mailing lists for servers with multiple IP addresses didn't fix the problem and only a hard-coded patch was sufficient to avoid being re-listed.
A message left on the james-users mailing list implies that this has happened to others too and may be down to the thread delay issue already mentioned in a TODO in the code above the setting of HELLO_NAME.