SUMMARY: Sendmail V8.9 & Reject=451

From: Charlie Mengler (
Date: Thu May 28 1998 - 10:05:39 CDT

Below is a copy of my original post.
I want to thank all those who replied.
The short answer is that my local DNS had gotten corrupted & confused.
By pointing my postoffice system to use the DNS on my ISP,
all the previously rejected messages got delivered OK!

This morning I stopped & restarted my local DNS & have
point the postoffice system back to the local DNS. It has
been two hours without any more REJECT=451 messages. So
I assuming that the problem has been resolved. I'm not
sure how, what or why my local DNS went crazy on me.
At least I know what to do should I see a similar
occurrance at any time in the future.


I've recently installed sendmail V8.9.0 on my post office system.
To make sure that I don't have any serious problems, I have logging
enabled so I have some visibility into what is happening. I'm now
seeing a decent number of entries that are similar to the following -

May 27 12:13:40 kirby sendmail[17153]: MAA17153: ruleset=check_mail,
arg1=<>, relay=[],
reject=451 <>... Sender domain must resolve

May 27 12:20:49 kirby sendmail[17216]: MAA17216: ruleset=check_mail,
arg1=<>, relay=[], reject=451
<>... Sender domain must resolve

Most messages seem to be getting delivered OK.
I'm looking for answers as to whether or not I have a problem.
If so, what are some possible fixes for this situation.

Charlie Mengler       
Anchor Chips                    Network Manager
619-613-7916(V)                 619-676-6896(F)
12396 World Trade Drive #212    San Diego, CA 92128-3788
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