RE: Multiple MX Records

  • From: "Mulnick, Al" <Al.Mulnick@xxxxxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 18 Dec 2003 10:58:07 -0500

Paul, it may be a worthwhile call to Microsoft Support to verify that you a)
have a bug and b) don't have a different issue such as DNS. 
 
 
Al

  _____  

From: paul_lemonidis@xxxxxxxxxxx [mailto:paul_lemonidis@xxxxxxxxxxx] 
Sent: Thursday, December 18, 2003 10:56 AM
To: [ExchangeList]
Subject: [exchangelist] RE: Multiple MX Records


http://www.MSExchange.org/

Hi Al
 
Many thanks for your prompt reply and help. Sorry I should have said. I am
running Exchange 2003 Build 6.5.6944.0 on Windows 2003.
 
From what you say it sounds like I may have to wait for a hotfix or service
pack to resolve this? Having said that I do seem to remember we did have the
problem on our old Exchange 2000 machine which had SP3 with the latest
rollup package. Fortunately it is not a major problem at present. Whilst it
could be me firewall my gut feeling is that it is not. Unfortunately I have
no way to prove or disprove that statement at present.
 
May thanks in advance.
 
Regards,
 
Paul Lemonidis.
 
 ----- Original Message ----- 

From: Mulnick,  <mailto:Al.Mulnick@xxxxxxxxxx> Al 
To: [ExchangeList] <mailto:exchangelist@xxxxxxxxxxxxx>  
Sent: Thursday, December 18, 2003 1:51 PM
Subject: [exchangelist] RE: Multiple MX Records

http://www.MSExchange.org/ <http://www.MSExchange.org/> 

If I recall correctly, there was an issue similar to this that was fixed in
later releases.  The problem was with the underlying SMTP (I think; it's
been some time).  What versions of OS and app are you running? 
 
The issue was something to do with the way the SMTP service would use MX
records.  It was very similar to what you describe.

  _____  

From: paul_lemonidis@xxxxxxxxxxx [mailto:paul_lemonidis@xxxxxxxxxxx] 
Sent: Thursday, December 18, 2003 8:31 AM
To: [ExchangeList]
Subject: [exchangelist] Multiple MX Records


http://www.MSExchange.org/

Hi All
 
Has anyone else come across this one? I have outbound messages queued up for
domains where there primary server is down. These queue up and are not
delivered which would seem fair enough on the face of it. Just one problem
the destination system has multiple MX records and the other hosts are up.
Why does Exchange refuse to use them? Even if I force the connection they do
not leave? Eventually they go of their own accord but this takes several
minutes or even hours? I cannot say at this stage if this is as a result of
the primary server coming back on line. I suspect it is.
 
> server 217.20.32.36
Default Server:  ns1.lon.ipmh.telecity.net
Address:  217.20.32.36
 
> set q=mx
> mtsn.org.uk
Server:  ns1.lon.ipmh.telecity.net
Address:  217.20.32.36
 
Non-authoritative answer:
mtsn.org.uk     MX preference = 10, mail exchanger =
scanmailext.easymail.va.ifl
.net
mtsn.org.uk     MX preference = 20, mail exchanger = mx1.easymail.va.ifl.net
mtsn.org.uk     MX preference = 30, mail exchanger = mx2.easymail.va.ifl.net
 
mtsn.org.uk     nameserver = dns2.rmplc.co.uk
mtsn.org.uk     nameserver = dns0.rmplc.co.uk
mtsn.org.uk     nameserver = dns1.rmplc.co.uk
scanmailext.easymail.va.ifl.net internet address = 213.18.255.195
mx1.easymail.va.ifl.net internet address = 213.18.248.112
mx2.easymail.va.ifl.net internet address = 213.18.248.112
>
 
I can telnet the second server just fine. The first one drops the connection
almost immediately. I suspect that is the answer? I am guessing that since
it does make a connection of sorts, albeit very briefly, it never tries the
second record as it thinks it is connected and thus never checks the other
MX records.
 
Above and below are relevant screen shots.
 
421 SMTP service not available, closing transmission channel
 


Connection to host lost.
 
Can someone tell me if I am correct and if there is any way around this
please. I know that strictly speaking, if my theory is correct, it could be
classed as a firewall issue at the remote end but that doesn't help me
deliver mail. The only short term way I see around this is to set up an
extra Virtual SMTP server and restrict the address space to just that domain
and forward to the second record host explicitly rather than using DNS.
Although that won't help with the trapped messages I suspect?
 
Any ideas, comments or suggestions please?
 
Many thanks in advance,
 
Regards,
 
Paul Lemonidis. 
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