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

[J G Miller]

At 22:37h, on Tuesday, March 01, 2016,
in message <56D65FF7.90302 at redowl.ca>,
on the subject of "Re: [Pkg-exim4-users] sporadic invalid helo -- setting primary_hostname",
Jonathan Addleman reported --
 
 > Thanks, that helps a lot! I'm a little wary of this fix though, because 
 > the docs say pretty clearly "Please refrain from using primary_hostname 

And did you read the sentences before that one?

QUOTE

   Debian's exim4 default configuration does not set primary_hostname. 

   Exim then defaults to uname() to find the host name.

   ---> If that call only returns one component, <---

   gethostbyname() or getipnodebyname() is used to obtain the fully qualified host name. 

UNQUOTE

You stated in your original message

QUOTE

    The bounce errors that I very occasionally get tell me that the HELO 
    identification was invalid, and I can see that exim is identifying 
    itself with 

                  ====>just the hostname<=====,
                 
    not the full domain. (i.e. sepia, instead of sepia.redowl.ca)

UNQUOTE

Therefore the problem is that occasionally the call to gethostbyname() or
getipnodebyname() is failing to get the full hostname with FQDN.

If you are afraid of setting primary_hostname, debug your system name calling
to ensure that gethostbyname() or getipnodebyname() return the fully qualified
hostname 100% of the time without failure.

That actually is a more worrying fundamental problem which you should be concerned
about that may well affect other things rather than the fix of setting primary_hostname.