RE: Multiple MX Records

  • From: <paul_lemonidis@xxxxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 18 Dec 2003 16:01:56 -0000

Hi Al

Many thanks for your help.

Regards,

Paul Lemonidis.

  ----- Original Message ----- 
  From: Mulnick, Al 
  To: [ExchangeList] 
  Sent: Thursday, December 18, 2003 3:58 PM
  Subject: [exchangelist] RE: Multiple MX Records


  http://www.MSExchange.org/

  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, Al 
    To: [ExchangeList] 
    Sent: Thursday, December 18, 2003 1:51 PM
    Subject: [exchangelist] RE: Multiple MX Records


    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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