No Valid Reverse DNS Entry?

Hi,

I have an exchange server setup and I'm using godaddy for my dns.  It's all working fine, except for when I send to this one user I a bounce back from there mail filter (MagicSpam) with the following:

Your server IP address [xxx.xxx.xxx.xxx] does not have a valid reverse DNS entry [xxx-xxx-xxx-xxx.cid.global-gateway.net]

I also looked up my ip in mxtoolbox and got "Reverse DNS does not contain the hostname"

A bit strange as I can send and receive from many other people including hotmail, gmail etc.  Do I need to create an rDNS record here in godaddy or my isp?

Thanks
ts11Asked:
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JohnBusiness Consultant (Owner)Commented:
Your Exchange server is behind your ISP (mail goes through the ISP) so you need to set up the reverse lookup with your ISP. They have to do it for you.

.... Thinkpads_User

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duttcomCommented:
I'm not sure what your setup is currently like, but it sounds like you may be pointing the MX records straight at your server's IP. Try this configuration (in GoDaddy's DNS management area)-

Assuming your Exchange server is set up as mail.yourdomain.com

mail.yourdomain.com A record points to XXX.XXX.XXX.XXX (the external IP address of your Exchange server)

yourdomain.com MX (10) record points to mail.yourdomain.com
ts11Author Commented:
In GoDaddy, I have a similar configuration.

A record that points to mail.mydomain.com using my exchange server's ip address.

MX record using @ pointing to smtp.mydomain.com
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Gareth GudgerSolution ArchitectCommented:
+1 to Thinkpads comment. A reverse records needs to be created at your ISP.
JohnBusiness Consultant (Owner)Commented:
See if GoDaddy Support can explain why the mail is bouncing if you think the configuration at GoDaddy is correct.

... Thinkpads_User
ts11Author Commented:
E-mailing my isp to see if they can assist.
JohnBusiness Consultant (Owner)Commented:
Let us know what they say. You should have that record at your ISP and they will surely assist.

.... Thinkpads_User
Gareth GudgerSolution ArchitectCommented:
Yea a lot of ISPs usually make you email their hostermaster@isp.com email address to make such changes.
Gareth GudgerSolution ArchitectCommented:
Also, what are you using for anti-spam, anti-virus filtering? If you are using something off-prem, then sometimes you can fix these issues by routing outbound mail through the same provider.
ts11Author Commented:
I'm using a mail marshal server on the same network.
Jeremy WeisingerSenior Network Consultant / EngineerCommented:
You're getting the NDR because the recipient's mail filter is checking for reverse DNS, as already been pointed out. So this record needs to be changed at the ISP, not GoDaddy. But you do need an A record pointing to your public IP address that the Exchange server uses. You would then have your ISP configure the PTR record to point to the name of the A record.

So:
At GoDaddy A record = mail.domain.com -> 123.123.123.123
At IPS PRT record = 123.123.123.123 -> mail.domain.com
ts11Author Commented:
My ISP has added this.  Thanks.
JohnBusiness Consultant (Owner)Commented:
@TS11 - Thanks for the update and I was happy to help.

... Thinkpads_User
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