Exchange bouncing a domain

[kdifs]

We are running win2k3SBS and we have a Sonicwall up front. One of our clients (our largest of course) cannot email us. Every time they send us an email, it bounces back undeliverable. We can send to them, but they cannot send to us even if it is a reply.

To our knowledge this is the only one it happens to. We are also running Ninja however it was doing that before the Ninja installation and Ninja would put the email into our spam folder not bounce it.

Is there something on the senders side that tries to ping our server or something? Is our firewall causing the issue?

I don't even know what to check on our side.

Please help. I don't know if it is our side or their side. Just looking for ANY input you guys may have.

Thanks!

Rob

 

[RichardHuang]

We used to have a similar problem at our side. We could send to all domain except one. The problem was the DNS issue. The DNS server our ISP provided couldn't resolve that domain's name. I called back to the ISP and they gave me new updated DNS server and the problem had gone since then.

 

[kdifs]

hmm. So, it is their DNS issue perhaps? I wonder if there is a way that I can contact their ISP.

We pass all of the tests on dnsstuff.com so I am having trouble figuring this one out...

 

[RichardHuang]

Did you check what the "bounced back" message say? It would be helpful to troubleshoot.

 

[kdifs]

Failed to send to identified host, bob@mydomain.com --Message non-deliverable."

 

[58sniper]

Hmmm.... that doesn't necessarily mean the problem is on your side.... Is there a DSN number (5.7.1, etc)?

Pat Richard, MCSE MCSA:Messaging CNA
Microsoft Exchange MVP

 

[ymeq123]

"We are also running Ninja however it was doing that before the Ninja installation and Ninja would put the email into our spam folder not bounce it."

?????????

Before Ninja it would bounce back to them also or no?
What put them into the spam folder?

So at one time you were getting the emails just in your spam folder?

Have you checked to see if your sonicwall's RBL is on?

 

[kdifs]

I am trying to get in contact with their computer tech so I can get the header info, etc on what is happening with the email.

The problem existed before Ninja was installed.
(if the problem were Ninja, Ninja would put their email into the spam folder not bounce it, however the email is not getting that far.)

We never received their emails.

Blacklist is disabled.

If I asked them to forward the bounced email to my home account would that have all of the header info I need to resolve the problem?

 

[ymeq123]

Ahhh! Thanks for the clarification kdifs. I read that sentence differently than it was intended!

 

[kdifs]

Sorry. I tend to do that. It sounds much different in my head.