Configure internal dns server to point to external mx records

I have an internal domain as an example is a Windows 2008 domain and has an internal dns server.  I have applications on the internal network that need to send email to  The email server for is hosted outside of the network and domain.  I have the mx records setup and can send email to the from outside but not from inside hosts of the domain.  How do I make the internal DNS server for send email traffic out to the mx records listed in external dns?
LVL 14
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

davealfordIt SupportCommented:
What is the mx setting for on the internal dns server?
dmwynneAuthor Commented:
Currently it is not set.  I tried setting it to the external mx records but it did not work.
You will need a reverse lookup record(PTR) for your Exchange Server in the external DNS for one thing.
Defend Against the Q2 Top Security Threats

Were you aware that overall malware worldwide was down a surprising 42% from Q1'18? Every quarter, the WatchGuard Threat Lab releases an Internet Security Report that analyzes the top threat trends impacting companies worldwide. Learn more by viewing our on-demand webinar today!

davealfordIt SupportCommented:
You would only need a PTR IF your email host insisted on it. Most do. To test it, Try sending an email from a PC inside your network to the IP address of you mail host. You will then see any error message it is giving -
telnet 'ip address of mail host' 25
If that doesn't work then it may be your mail host requires PTR. If it does work then all you should need is to add an MX record for The MX record SHOULD be an A record NOT an IP address.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Okay, your internal AD domain is Your email servers for are external, and you have internal mail servers that need to be able to relay mail to You have an internal DNS zone for Do I have things correct?

If this is the case, you need to add MX records on your internal DNS zone that match the public DNS records, AND you also need to include the correct A records for hosts that are in


@ MX 50
@ MX 40
@ MX 20
mail2 A
smtp A
dmwynneAuthor Commented:
I added the mx records again and it seems to be working, not sure why it did not work the first time.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.