[cobalt-users] 451 mail undeliverable SOLVED

[James Riordon <James@xxxxxxxxxx>]

Just thought you might all like to know.

I have been having one hell of a time figuring out why some sites 
accept email and some don't. The ones that dont kick back the message 
'451 mail undeliverable after 4 hours' will keep trying for 5 days.

I searched high and low for an answer and finally found it by 
checking each and every .conf file I could find.

/etc/resolv.conf was missing our DNS server. It had our domain as a 
search path and it had our ISP's nameservers in it but it did not 
have ours. After adding in our nameserver plus IP and then restarting 
sendmail, I gleefully watched the mailq slip away until it was empty.

Hope this helps some people out with some of there problems.

J