Re: Resolving External MTA MX Records Incorrectly

We don't use a Smarthost entry in our SMTP Connector. We just have our
Front-End Server resolving the IP addresses and sending the e-mail directly
to the Company's E-mail server via the internet.

We wouldn't use a Third Party Smarthost such as an ISP's to send e-mail
because we fundamentally try to avoid passing company information over any
3rd party environment.

Any other suggestion on how to resolve the problem of resolving MX records
incorrectly?
--
ExchangeFTW
Exchange Messaging Engineer


"John Oliver, Jr. [MVP]" wrote:

Are you using a Smarthost such as your ISP in your SMTP connector? I am
seeing more ISP's such as AOL, Hotmail, etc. blocking IP addresses from
smaller IP blocks such as DSL circuits. This is usually resolved by using a
Smarthost entry in your SMTP connector. Typically its your ISP's mail
servers or third party such as filtering services.

--
John Oliver, Jr
MCSE, MCT, CCNA
Exchange MVP 2007
Microsoft Certified Partner


"ExchangeFTW" <ExchangeFTW@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:647543BE-6ADC-4F62-9CA8-3395F760A1B5@xxxxxxxxxxxxxxxx
Occasionally users in our Environment will receive NDRs when they send an
e-mail to someone they correspond with regularly.

When I check the SMTP Logs to see why this is happening I'm finding
connection denied responses.

I then do an NSLookup
set type=mx
[External Company Domain]
Then get a list of the Company's MX records.

Once I find they IP of their e-mail MXs and compare that to the IP of the
Connection Denied entry in the SMTP Log they aren't the same as the IP of
the
external e-mail MX IPs.

Usually it is the IP they have for their Reverse DNS Entry.
This is happening on a Win2k3 SP2 - E2k3 Sp2 Front-end Server.
This server uses a Win2k3 SP2 DC with DNS on it to resolve External DNS
Requests.

Do you have any idea why this happens and what I can do to keep the issue
from happening?

Thanks

--
ExchangeFTW
Exchange Messaging Engineer

.

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