hotmail undeliverable

By mj5410 ·
ONe of my customers is using SBS with Exchange and a sonic firewall. I opened the firewall up so they could access some https sites for finacial stuff and now when they try to emaila aclient with a hotmail addres it bounces and says not deliverable. Ive been looking on the hotmail site and not really found anything that relates to this error.
any help out there?

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by Nimmo In reply to hotmail undeliverable

The bounce back should explain the reason, such as spam looking or something else.

You may want to advise the person to change the subject line to something simple and also tell them to be careful what they put in it.

Different servers filter in different ways but you'll find most if not all filter content in the subject line, text in the body, and look at headers.

Enter your domain in here to do a blacklist lookup, just to be sure your not blacklisted anywhere.

This is most likely not the issue but check to make sure you have a valid reverse lookup entry.

Some servers filtering software will bounce email if they do a reverse lookup on the email and find the sending server isn't the one that they did the lookup on.

What I mean is that if you send an email from your domain (, your email will then go to your ISP, which is then forwarded to the destination server.

If the reverse lookup is pointing at the ISP's mail server, the destination server will it treats it as a spoofed email and will bounce it, because the sending address is ( but the reverse lookup is (ISP's server address).

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found answer

by mj5410 In reply to Undeliverable

Thanks for your response, I found a thread in the Microsoft forums and they had the answer i needed to fix this problem. the DNS servers were part of the problem. I set up different DNS in the Exchange Virtual SMTP Server and then added a line in registry xexchng50 or something like that. between the 2 items this problem was taken care of.
thanks again

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Good to hear its fixed

by Nimmo In reply to found answer

Interesting resolution though.

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