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Exchange 2010: Sending issues

Posted on 2011-02-28
Medium Priority
Last Modified: 2012-05-11
This mornign a user tried to send an email to a customer and received the following error response:

CUSTOMERDOMAINNAME.com refected your message to the following e-mail addresses:

Customer Name (customer.name@customerdomain.com)

customerdomainname.com gave this error:
<customer.name@customerdomain.com>... Domain of sender OurUser@mail.OurDomain.com does not exist

Your message couldn't be delivered because you weren't recognized as a valid sender. Make sure your sending address is set up correctly and try to send the message again. If the problem continues, please contact your helpdesk.

Is this a problem on our end?  We just migrated to this server over two weeks ago, but this is the first time we have had a problem sending outside of our domain.
Question by:VoodooFrog
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LVL 76

Expert Comment

by:Alan Hardisty
ID: 34997256
Please check that your server is RFC compliant and that it is configured correctly.  My article should help you:


With Exchange 2010 - check the SEND Connector FQDN and make sure that is displays a resolvable address in DNS externally and that this FQDN resolves back to your server's sending IP Address.
LVL 10

Expert Comment

by:Muzafar Momin
ID: 34997281
please check your MX and PTR
LVL 11

Expert Comment

ID: 34997453
Can you please confirm that you have a SPF-record defined for your domain.
I've come across this error before when no rDNS record nor SPF could be found for your domain.

Because of that, the recipient's spam-filter cannot verify that your server's IP-address is allowed to send mails for your domain.

Furthermore, make sure that the FQDN on the Send connector is filled in correctly.

Kind regards,

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Author Comment

ID: 35000166
Alright, I think this may be the SPF record.

Now, I am a little concerned how the dns is set up.  Our mail server has the FQDN send connector of mail.OurDomain.com.  

-The domain OurDomain.com is hosted offsite.  
-The DNS record for OurDomain.com has a an MX record of mail.OurDomain.com.
-Mail.OurDomain.com resolves to our Exchange server's external IP Address.
-I have changed the SPF on the DNS for OurDomain.com to allow sending from mail.OurDomain.com and the IP Address of mail.OurDomain.com.
-mail.OurDomain.com has a DNS A record, but no SPF, MX, PTR, NS, or SOA records.

For the reverse lookup tests, do I put in the domain name or the IP address?

Let me know if I need to make changes to anything.

LVL 11

Accepted Solution

MichaelVH earned 1000 total points
ID: 35000235

the way you put it there, it seems to be quite okay :)

However; I'm not clear what you refer to with "For the reverse lookup tests, do I put in the domain name or the IP address?"; what do you mean?

LVL 76

Expert Comment

by:Alan Hardisty
ID: 35000274
You can use nslookup for reverse DNS:

In a command prompt type the following:

nslookup mail.domain.com

nslookup your-fixed-ip-address

The first check should return your IP address, the second should return mail.domain.con
LVL 76

Expert Comment

by:Alan Hardisty
ID: 35000287
You can also use the following site to check and test your SPF record:


Author Comment

ID: 35000347
MichaelVH, I was asking because when I put in the fixed external IP into a reverse lookup I am not getting mail.domain.com

nslookup mail.domain.com returns the fixed IP appropriately.

nslookup fixed-ip-address returns a domain name that I assume our ISP uses to identify our IP address, not mail.domain.com as I would expect.

LVL 76

Assisted Solution

by:Alan Hardisty
Alan Hardisty earned 1000 total points
ID: 35000383
Okay - so your Reverse DNS is not configured properly and you will need to call your ISP and get them to configure Reverse DNS as mail.domain.com to match your FQDN on your SEND connector.

Author Comment

ID: 35000995
OK, I am working on getting the reverse lookup fixed.

In the meanwhile, does there need to be an SPF record for mail.domain.com?
LVL 76

Expert Comment

by:Alan Hardisty
ID: 35001044
You don't NEED an SPF record - it is better to not have one than to have an incorrect one, but it can be good to reduce spam and to help tell the world the mail servers that are authorised to send mail on behalf of your domain.

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