[Pkg-exim4-users] sporadic invalid helo -- setting primary_hostname

[J G Miller]

At 14:16h, on Wednesday, March 02, 2016,
in message <56D73C07.20704 at redowl.ca>,
on the subject of "Re: [Pkg-exim4-users] sporadic invalid helo -- setting primary_hostname",
Jonathan Addleman pondered -

 > One thing that I thought *might* be related is that my hosts line showed 
 > two 127.0.0.1 lines, one for localhost, and another for the actual 
 > hostname and fqdn.

But do you also have an entry for the network interface device (not the loopback
127.0.0.1) that exim4 is listening on?

 > Some googling showed that there are cases where that 
 > could be problematic..

Yes having two possibly conflicting entries is a problem since how
does the name lookup know which is the one you really want to use?  ;+}

 > I changed the hostname one to 127.0.1.1

My suggestion would be in /etc/hosts to have

127.0.0.1	localhost.localdomain	localhost

(localdomain is chosen rather than local so as not to conflict
with Avahi/Bonjour local) and then for your network interface
that exim4 is listening on

172.86.178.126	sepia.redowl.CA		sepia

or whatever IP (non loopback) you do actually use.

So give that a try without doing the forced primary host name
to see if that makes any difference, and at minimum, it will
indicate whether or not the issue of intermittent bad name lookups
is coming from that or is in fact arising from a different misconfiguration.

Golden rule when trying to fix these problems (which often results in
other problems being discovered and fixed) -- only change one thing at a time
and see if it makes any difference.