Exchange Messages not being recevied by some clients

Tim
Tim used Ask the Experts™
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I have recently had issues with my Exchange 2003 server, OWA mis-configured and being placed on blacklists at the beginning of the week. I now have OWA working correctly and have been removed from all the blacklists however when I send an email to one of my customers they never get the email. the next day i get a delay report then the following day i get an NDR email. I have sent emails to that customer and have looked in the message tracking of Exchange and it says "Message Transferred to through SMTP"  which I assume means it was sent out however I don't see any of the receiving servers like I would if I sent to a Yahoo email. How can I find what is happening to these emails. I can send to the customer from my Yahoo account and they get it but not from our Exchange account.
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Commented:
http://forums.msexchange.org/m_1800463634/mpage_1/key_/tm.htm

This discussion may help sounds like the same issue.
I agree with alsh00 - the article he linked includes good info on SMTP logging, which is critical in situations like these.
TimSr. System Admin

Author

Commented:
OK, that helped me but made issues more complicated. When I ran the ExTRA tool decribed in the forum it told me

The fully-qualified domain name of SMTP virtual server 'Default SMTP Virtual Server' on server <machinename> does not match the DNS resolved server name. This may cause mail routing problems. SMTP virtual server: mail.<subdomain>.com. DNS resolved server name: <machinename>.<domain>.com.

We had to create a sub-domain because our domain name had been taken on the net.

I tried changing the name in the SMTP virtual server but when I check the name it says invalid yet when I look on the DNS server it has that name created. It might have something to do with the subdomain but don't know how to resovle.
TimSr. System Admin

Author

Commented:
OK, I thought I fixed it however it doesn't look like I did. I ran some tests using MXToolbox.com and my MX, PTR, A records all point to mail.subdomain.com but when I ran a test email from that site my spamserver answered the call as spamserver.subdomain.com. Would this cause the emails to be rejected by servers doing reverse dns? When I check reverse dns it shows mail.subdomain.com but this test makes me think different. Confused.
Distinguished Expert 2018
Commented:
Actually, I would be inclined to think just that if reverse DNS gives a result that does not match. Try fixing things involving the name your spamserver shows, and your life should ideally be it. Try asking people you know that work for companies that use reverse DNS lookups, and test sending to email addresses at those places. If you're getting bouncebacks, then looks like you have your answer.

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