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Emails bouncing back asking for domain name

Out of the blue this morning, a number of users are having bounce back with this message from proofpoint, never seen this one before (pic attached):

The reverse hostname of this IP appears to come from a DHCP block. If this is actually a static IP with an email server, change the host name (or have your ISP change it) to something identifiable. For example: mail.domainname.com

Where do I go to change it ?? Thanks
2 Solutions
Daniel HelgenbergerCommented:
do an nslookup of the IP.
Please ask your ISP - they probably changed something in DNS or proofprint chained ther spam policy. Most commonly you can set a reverse name for static IPs in the Web admin center of your ISP. If it was never set, do as the massage says!
If I'm correct, BT Openworld is a consumer based broadband solution ? Usually you don't have the right for a custom reverse DNS entry (even if you're willing to pay a fee).
Probably you have to ask for a business type of connection (more expensive!), after which you can change the reverse DNS entry yourself or have the ISP do it for you for a minor surcharge. Sometimes it's not even necessary, as your business connection's IP will be from another pool which has not been marked as "DHCP block".
Simon Butler (Sembee)ConsultantCommented:
Are you on a business connection with BT?
If so, you can get BT to change the PTR record to match your MX record host name.

Send an email to reverse.dns@btbroadbandoffice.com

Dear Sirs,
Please can you change the PTR on our static IP address xxx.xxx.xxx.xxx
 to host.example.com .
Any queries, please let me know.
Kind regards,

Replace with your actual email and domain name.

If you are not on a business connection then you will need to either
a. Change to a business class connection so the PTR can be set.
b. Change to use BT's smart hsot for outbound email. You have to tell BT what your domain name is to be able to do that.

CombemartinAuthor Commented:
Thanks Simon & Kim, it is a business line but we are also going Fibra later next week but will keep the current BB as a backup, so I best wait until the new Business Infinity2 to do this in one swoop.
Thanks guys.
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