Old Exchange server - new ISP cannot provide rDNS

Adam D
Adam D used Ask the Experts™
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I have an older exchange server which is working without a problem on my current ISP.  I had to switch ISP's recently and my old ISP will be disconnected shortly.

Unfortunately, even though I WAS told my new ISP can provide rDNS for my on-premises email server, I am now being told they cannot.

I have a "persistent-IP" which is ALMOST a static public IP, but it must be from a block of public IP's they have in which I am probably being natted.

So, is there a way to setup a third-party rDNS so my emails from my on-premises server do not end up in spam or bounce?

Thanks.
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Principal Software Engineer
Commented:
Whether by classical RDNS or delegated CNAME, reverse DNS can only be supplied by (or with the cooperation of) the owner of the IP block in which the IP address is located.  So if the ISP refuses to provide RDNS, you're out of luck there.

There are two alternatives:

a) Make the ISP either live up to their promise, or let you out of the contract with no termination fee as this is a significant breach of the contract terms.  Since RDNS is mandatory to run an email server, your legal department must have made "RDNS will be provided" as part of the contract.  If they didn't, drop in and have a little chat with them and explain that email company-wide will soon fail due to their little oversight.

b) Tell the ISP you are not pleased and will drop the contract as soon as it is possible to break it, and in the meantime sign up with an outgoing email forwarder such as SMTP2Go.  SMTP2Go will forward up to 2000 messages per month free, and a small fraction of a cent after that.  Actually I find this more convenient than running direct outgoing email, as they take care of all the routine issues for me.
MASEE Solution Guide - Technical Dept Head
Most Valuable Expert 2017

Commented:
If your ISP is not ready to create PTR for you as commented above it is better to  find another ISP who can create PTR (RDNS) for you.
Adam DIT Solutions Developer

Author

Commented:
Thanks for getting back to me.

Apparently the ISP is "unable" (through incompetence or otherwise) to provide rDNS/PTR records and yes I can get out of the contract but I am very limited in my choices of ISP's in my location.  Essentially, they are it; as my old provider is no longer a viable alternative for many reasons.

I sent a note to SMTP2Go and they say their service will work with my Exchange server (I am running 2010 as part of an old SBS 2011 server) which works fine and which I am not replacing at this time.

Any thoughts on using them (or others) with the server and any security risk to the email content in doing so?

Thanks.
Dr. KlahnPrincipal Software Engineer

Commented:
Outgoing email routed through SMTP2Go is encrypted using SSL/TLS, so it is as secure (as it leaves your premises) as it is possible for normal email to be.  From that point forward it depends on whether the recipient's site and any intervening sites support SSL/TLS.

You will need to update your SPF and DKIM to reflect SMTP2Go as the new authorized outgoing source.
Adam DIT Solutions Developer

Author

Commented:
Thanks Dr. Klahn.  I think this will be the way to go due to my current situation.  :)  I appreciate the help and quick response.

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