[Pkg-exim4-users] sporadic invalid helo

[Jonathan Addleman]

Hello,

I've been using exim for many, many years, though rarely had to change 
anything, so I'm not particularly well-versed in the config. Since 
moving to a new host, I've been having troubles with sent mail either 
being rejected, or silently ignored by many recipients. Most of the 
time, it works, but occasionally not.

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). The vast majority of the time, it does identify 
with the FQDN.

I'm pretty sure the problem lies in 
/etc/exim/conf.d/transport/10_exim4-config_transport-macros, with the 
line REMOTE_SMTP_HELO_DATA=${lookup dnsdb 
{ptr=$sending_ip_address}{$value}{$primary_hostname}}

When the lookup succeeds, the HELO uses the proper domain. But it seems 
my host has a slightly wonky DNS server, and it occasionally fails. In 
that case, it uses $primary_hostname. From the docs I've read, 
(https://wiki.debian.org/PkgExim4UserFAQ#How_does_exim_find_out_its_host_name_to_use_in_HELO.2FEHLO.3F) 
this value is not set, and should be getting the full domain, but it 
seems to be only getting the hostname.

'hostname -f' does return the full sepia.redowl.ca name... Is there some 
additional configuration that I might need to do so that exim gets that 
same value?

Thanks for any suggestions you can offer. If it matters, I'm using the 
most recent stable release, 4.84-8+deb8u2.

-- 
Jonathan Addleman - http://www.redowl.ca