[Exim] How to handle bogus MX records

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Author: Paul Kanz
Date:  
To: exim-users
Subject: [Exim] How to handle bogus MX records
What is the best way with Exim 3.x to handle sites that have bogus MX
records - ones that list 0.0.0.0 as the IP address. A good example is
myvzw.com:

$ dig myvzw.com mx

; <<>> DiG 8.2 <<>> myvzw.com mx
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 4, ADDITIONAL: 6
;; QUERY SECTION:
;;      myvzw.com, type = MX, class = IN


;; ANSWER SECTION:
myvzw.com.              29M IN MX       10 vzw1.re-routeserver.com.
myvzw.com.              29M IN MX       20 vzw2.re-routeserver.com.


;; AUTHORITY SECTION:
myvzw.com.              1d21h53m50s IN NS  CAWCNS1.myvzw.com.
myvzw.com.              1d21h53m50s IN NS  CAWCNS2.myvzw.com.
myvzw.com.              1d21h53m50s IN NS  NJBDNS1.myvzw.com.
myvzw.com.              1d21h53m50s IN NS  NJBDNS2.myvzw.com.


;; ADDITIONAL SECTION:
vzw1.re-routeserver.com.  9h53m55s IN A  0.0.0.0
vzw2.re-routeserver.com.  9h53m55s IN A  0.0.0.0
CAWCNS1.myvzw.com.      1d21h53m50s IN A  66.174.6.71
CAWCNS2.myvzw.com.      1d21h53m50s IN A  66.174.6.72
NJBDNS1.myvzw.com.      1d21h53m50s IN A  66.174.3.71
NJBDNS2.myvzw.com.      1d21h53m50s IN A  66.174.3.72


;; Total query time: 3 msec
;; FROM: pdx-dns1 to SERVER: default -- 192.168.175.252
;; WHEN: Tue Dec 31 14:41:01 2002
;; MSG SIZE sent: 27 rcvd: 271

With Exim 3.33, any mail that is going to a host that has 0.0.0.0 as the
IP address, Exim seems to get into a loop and trys to send to it MANY
times. In the mean time, the exim_main.log file is filling up with the
send attempts and the system load goes up (from .02 to .80).

My current work-around is using a filter that drops the mail. Is there a
better way of handling this?

Thanks,
-Paul