Ironport: Cannot find your hostname/your server ip address x.x.x.x is missing a reverse DNS entry

[Mady]

Hi Team,

Please help me on my issue, we have Cisco Ironport but we have problem on sending our emails. I attached here the error we encountered for two emails. We are advised to add a ptr record but unfortunately, our service provider was unable to add it. Is there any other resolution that can solve this issue?

Thank you very much.

Regards,

Mady

[Philip D'Ath]

If you are using ISP provided address space then it is absolutely the job of the ISP to provide the reverse DNS service.  Go back and ask them again.  Ask to talk to someone more senior if the first person does not understand.

Make sure you tell them you need a reverse DNS entry added.

[Mady]

Hi Philip,

Do you think once we added a reverse DNS entry,it will resolve the attached error? 

Thank you very much!

Regards,

Mady

[Philip D'Ath]

As long as it matches your forward DNS entry, yes.

I'm surprised you can get much email delivered with no reverse DNS entry.

[Mady]

Thank you again Philip, I will talk to our ISP for this issue. I am just wondering if is there any other workaround for this issue? If ISP will insist that they cannot add a reverse DNS?

[Philip D'Ath]

1. Change ISPs.
2. Use a smart forwarder (aka relay) (perhaps provided by your ISP) and forward all your traffic via them.

[Mady]

Can you further explain to me the smart forwarder? :) if I use a smart forwarder, is this also requires reverse dns entry?

[Philip D'Ath]

With a smart forwarder (or relay) you tell your Ironport to send all outbound email to another email server and have that server deliver the email on your behalf.

You won't need a reverse DNS entry for this.  Personally, I would want the reverse DNS entry and to do my own email delivery.

[Mady]

How can I create a smart forwarder? Do I have to pay for another email server for this? Thank you very much. I really appreciate your help.:)

[Philip D'Ath]

ISPs usually supply this service as part of their service.  You should not have to pay extra for it.

[Mady]

Noted Philip. Will just contact my ISP again for the reverse DNS.

Thank you very much!