How to avoid stopping work with the mail queue?

Question

Email

Googling seems to be an old problem, but I haven't found a definitive answer yet. The point is. Periodically, items marked as:
host map: lookup (kem.ru): deferred
The server works to send messages "to the world", as well as to deliver local messages to another server via /etc/mail/mailertable (that is, to mailertable there is an entry like "domain.ru smtp:[10.1.1.56]" - and all letters to the addresses [email protected], [email protected], etc. - go to the server 10.1.1.56).
Deferred is usually marked spam because it occurs when DNS cannot find an A or MX record for a given domain. And figs would be with him. The question is that mail stops being transmitted on 10.1.1.56 - all of it is also marked as Deferred! Restarting sendmail is not enough to fix the situation. You need to stop sendmail, remove the spam email, remove it from /var/spool/mquere/.hoststat/56./1./1. file 10 and restart sendmail - and then the remaining queue will immediately disappear.
Question - what to do so that 10.1.1.56 is not marked with the Deferred status? Spam don't care, let him hang out in the queue.