Half-Grey-Listing (Update 03)

Posted on July 7, 2017 by Hendrik Jäger

Half-Grey Listing

Concepts of nolisting and greylisting should be known.

Imagine this setup:

example.org         IN  MX  05
example.org         IN  MX  50
example.org         IN  MX  99

All addresses are on the same host running exim. Exim would go through the whole process (almost – since most stuff is rejected anyway, one may want to optimize here) as normal, but will tempreject (almost – abuse@ and postmaster@ should probably be unfiltered, just to make sure) everything on and

Is anything wrong about this (WRT to RFCs)? What might go wrong?


It seems there are a few appliances that can’t properly deal with this setup:

I contacted all of them and the feedback I got so far:

I disabled the setup for now, though, too many broken sites out there …


Setup running on the mostly unused domain hj-systems.de.

You can send me a testmail to test@hj-systems.de to see whether your email-infrastructure is able to deliver it.

If you have trouble getting the mails out, send to postmaster@hj-systems.de, which should always be deliverable.


Gmail fails as well. I successively moved the ‘defer’ statement to sooner stages of the smtp dialog:

In exim terms:

Now, with the defer in acl_smtp_connect, it seems to work fine.