[CentOS] Mail has quit working

Thu Aug 30 22:22:45 UTC 2018
Gordon Messmer <gordon.messmer at gmail.com>

On 08/29/2018 06:54 PM, TE Dukes wrote:
> Added back the IPV6 to /etc/hosts a couple days ago for grins and giggles.
> No longer getting IPV6 errors in logwatch for bind. Everything working.
> I think removing my ISP's nameservers from /etc/resolv.conf was the fix.

I just caught up on the thread.  It looks like the core issue was never 
actually resolved:  "getent hosts localhost" still doesn't return the 
expected result, right?

     $ getent hosts localhost
     ::1             localhost localhost.localdomain localhost6 
     $ grep ^hosts /etc/nsswitch.conf
     hosts:      files dns myhostname

If you're not getting the expected result from "getent", and if your 
nsswitch.conf lists "files", then glibc is somehow broken.  "rpm -V 
glibc" might tell you how, or it might not.  Could be that glibc can't 
load /lib64/libnss_files.so.2.

In any case, DNS is now providing you with a result for "localhost", and 
that'll work around most of the problems, but you really should take 
steps to fix glibc.  With something that low-level broken, I'd urge you 
to build a new system from scratch, and automate the build with some 
configuration management tool this time, so that the next time you need 
to rebuild, you can do it quickly.