Multiple MX Records

  • From: <paul_lemonidis@xxxxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 18 Dec 2003 13:31:01 -0000

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
Default Server:

> set q=mx

Non-authoritative answer:     MX preference = 10, mail exchanger =
net     MX preference = 20, mail exchanger =     MX preference = 30, mail exchanger =     nameserver =     nameserver =     nameserver = internet address = internet address = internet address =

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,


Paul Lemonidis. 

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