How to solve the problem with sendmail and missing domain?

Question

Domain Name System

There is one very old problem with sendmail.
The config says:

define(`confHOST_STATUS_DIRECTORY', `.hoststat')dnl

The /var/spool/mqueue/.hoststat directory has a bunch of subdirectories where sendmail keeps some kind of record. The problem arises when a letter arrives in which a bunch of spam addresses go to any hat. If there is an address among them that sendmail cannot resolve, then it takes on the pose of a summer resident and either starts to slow down altogether and stops processing incoming mail, or it works but is extremely slow.
What can be done? Increase the number of queues? Set timeout for DNS query?

Answer 1

Filter spam.
Or bury Sendmail.
To use it, you need to understand very well how to cook it. At some point, my old mailer simply began to believe that everyone in the trusted network was illegally trying to relay through it. The post office is up. And I did not find a better option than to migrate to Exim in a couple of hours.
PS Exim, objectively speaking, is quite full of holes in comparison with postfix, and is given as an example. Although there have been no incidents so far.