10-06-04 10:54 PM
OK... I figured this out... I hope this helps *MANY*
people out there suffering from the pain-in-the-
rear '5.7.1 unable to relay for' messages, or 'relaying
denied' messages, or '550 <domain> does not recognize
your computer <ip> as connecting from a <domain>
connection' messages, or '503 This mail server requires
authentication' messages, or '550 relaying prohibited by
administrator' messages... That's about all what I
experienced... This goes for the SMTP Server service
running under IIS5, IIS6, Exchange 2000, 2003... all the
same.
The answer: In the SMTP properties -> General Tab
Make *SURE* that the IP address field does *NOT* say "All
Unassigned", but make sure it has an actual, valid IP
address in there.
Doing that made all my troubles go away... <sigh> What a
thing to lose hair over... 
L8r,
Mike
vnvjeep@hotmail.com
>-----Original Message-----
>Hi All,
>
>I'm having a horrible time only with mass mailouts (with
>recipients in the BCC field), and get a ton of "5.7.1
>unable to relay for" type NDRs. Normal day-to-day email
>works just fine.
>
>When looking at the event logs, I'm finding that the
SMTP
>service is actually trying to deliver some of these
>emails to webservers and other A record type hosts,
>instead of MX hosts! Wa wa what???
>
>Then, I noticed a post in Google from Microsoft saying
>that "If an MX record is not found Exchange will attempt
>to deliver to an A record. This tells me the Exchange
>server is querying DNS an not getting the correct
>answer." (see below)
>
>(http://groups.google.com/groups?
>hl=en&lr=&safe=off&threadm=bX8DT%230aEHA.2804%
>40cpmsftngxa06.phx.gbl&rnum=1&prev=/groups%3Fq%3Dmx%
> 2Bunable%2Brelay%2Bsmtp%2Bwindows%2B2003
%26hl%3Den%26lr%
> 3D%26safe%3Doff%26selm%3DbX8DT%25230aEHA
.2804%
>2540cpmsftngxa06.phx.gbl%26rnum%3D1)
>
>Because the mailout is so big, it would seem to me like
>the SMTP service isn't giving itself enough time to grab
>these MX records, and opting for the A records instead.
>When I do an NSLOOKUP from the server itself, it's able
>to grab the MX record without any problems... plus, I
can
>telnet over port 25 without any problems to these MX
>hosts...
>
>Does anyone know if there is there any way to force the
>SMTP service to only look for MX records, and not fall
>back to A records... or perhaps increase the timeout
>before falling back to A records?
>
>To explain my environment... I have a caching-only DNS
>server (not using forwarders) running on this
Win2k3/IIS6
>machine to speed up DNS queries... It's also sitting
>behind an ISA 2000 server firewall. The ISA server is
>hooked up to a T1.
>
>I appreciate your response immensely!
>
>.
>
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