For some time now, I have been getting these entries in my syslog:
Dec 21 21:49:13 c52226 sendmail[26377]: fBLKnDH26377: Authentication-Warning: c52226.upc-c.chello.nl: Host [202.58.118.7] claimed to be lists2.suse.com [cut] What is going on, and more important: how do I set sendmail on a less secure-mode? It denies certain hosts because supposedly the 'domains do not resolve'...
Don't know if this will solve everything, but edit /etc/sendmail.cf. Look for a line like this:
O PrivacyOptions=needmailhelo,novrfy,noexpn,noverb
Yours probably has one more item: "authwarnings". Remove that and restart sendmail:
rcsendmail restart
Yes, that helped! But what about the 'Sender domain must resolve'-messages I get? My domain for example is perfectly resolveable, but doesn't have a primary IP address. No RR record for any host that is. Is that the cause? Rogier Maas