I have need to have Exim imitate the Postfix policy server protocol,
in order to interface with Postgrey running on another server. Its
pretty simple, but the existing examples for this are mostly
imperfect, so I'm sprucing things up a bit and trying to get it right.
The protocol is described on the Postfix site:
http://www.postfix.org/SMTPD_POLICY_README.html#protocol
The particular field I'm looking for input on is the "instance"
field. The documentation says:
instance=123.456.7
The "instance" attribute value can be used to correlate different
requests regarding the same message delivery.
The best example I can find for doing this in Exim is in this article:
http://blog.schalanda.name/archives/118-Exim-4-and-policyd-weight.html
I'll not post the sordid details of the configuration here, but the
line that handles the instance variable goes like this:
instance=$sender_host_address.$sender_address.$sender_helo_name\n\n
As far as I can tell this is meant to construct a "unique" identifier
for that particular email, but this construction doesn't appear
particularly unique to me. Can anyone who knows enough about both
Exim and Postfix speak to this? Would something like the following
be a better construction:
instance=$sender_host_address.$sender_helo_name.$message_exim_id\n\n
I know this is a pretty obscure question, but I want to get this
right so I don't have to think about it any more. Thanks!
--
Mark Edwards
