troubleshooting Question

DNS - Mx Record Issues

Avatar of Simon
SimonFlag for Canada asked on
ExchangeInternet Protocols
7 Comments2 Solutions378 ViewsLast Modified:
Can't send an email to one of my customers, it stays in the outbound queue trying to connect.
After 2 days it would time-out with 4.4.7 Error.
The customer recently changed their mail system to use
However, they still have the old Mx record published as well which doesn't even work.

Here is my main concern: When using the NsLookup (set q=mx) from my in-house DNS server (which is connected outside with my ISP dns servers) I can only see their old Mx record. When testing with a different dns public server (Google I actually see both Mx records.

I checked my firewall (router) and DNS queries on port 53 are not getting blocked.
Other hosts seem to be resolving fine.
I also removed the old pointer in my dns cache for this specific domain, but it still comes up with old Mx record/IP address only.

I am not sure what to test and do at this point; I did ask them to remove their old MX record, not sure if that will resolve my issue. They also told me that I am not blacklisted on their new server (not blacklisted in general).

Thanks for your help, much appreciated.
Join our community to see this answer!
Unlock 2 Answers and 7 Comments.
Start Free Trial
Learn from the best

Network and collaborate with thousands of CTOs, CISOs, and IT Pros rooting for you and your success.

Andrew Hancock - VMware vExpert
See if this solution works for you by signing up for a 7 day free trial.
Unlock 2 Answers and 7 Comments.
Try for 7 days

”The time we save is the biggest benefit of E-E to our team. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange.

-Mike Kapnisakis, Warner Bros