[Exim] lookuphost, MX and A records discrepancy ?

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Autor: Bernard Stern
Datum:  
To: exim-users
Betreff: [Exim] lookuphost, MX and A records discrepancy ?
Hello,

My MTA acts as a relay host for the news moderators aliases. As such,
I have to cope with many bounces from badly configured newshosts.
Most such bouncing addresses look like

news@???

My aim is to get rid of such bounces after a much shorter time
than normal mail. The first idea is to play with the retry rules.
Howerver, since it is not possible to match local parts for
non local domains within retry rules, I had to do some other tweak.
Thanks to Philips idea, I could partially solve my problem.
I have following router:

news_bounce:
driver = lookuphost
domains = *
local_parts = news
condition = ${if and {{> {$message_age}{43200}}{eq {$sender_address}{""}}} {yes}{no}}
# 43200 s = 12 h
transport = trash

This works well, but apparently only for domains that have an
MX record. This does not work for other domains (mmhhh... I wrote
apparently because I did some checks but I did not check every
instance of such hosts from my log files :-) ).
As I understand the spec, MX records then A records are looked up,
so this router should work for both types of domains. While
MX-domain bounces vanish as expected after 12+ hours, A-domain
bounces keep stuck in the "queue".
Looking at the spec, there is the mx_domains options, but as
I understand the spec, this would not meet my needs.
So my question: is there an inherent difference in the treatment
of hosts with and without MX record using only these options?

(Exim 3.15, solaris 7)

Regards,

Bernard Stern, SWITCH

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