Having some bad mail server problems

Hi guys,

Could use some help here. We've been having users complain that their email is either bouncing back to them or they get message delayed emails and finally it bounces back. I checked all the usual things like reversedns, blocklists, etc, but it continues to happen. Currently, if I look in the queue I see a few 421 4.2.1 errors and the message keep retrying. We do have two Interner connections here and the mail could go out on both, but the DNS is set up correctly.

Any help would be appreciated! I also ran the Microsoft Remote connection tests and it passed on both IP's:


      Performing Outbound SMTP Test
       The outbound SMTP test was successful.
       
      Additional Details
       
Elapsed Time: 19372 ms.
       
      Test Steps
       
      Attempting reverse DNS lookup for IP address 40.141.69.66.
       The Microsoft Connectivity Analyzer successfully resolved IP address 40.141.69.66 via reverse DNS lookup.
       
      Additional Details
      Performing Real-Time Black Hole List (RBL) Test
       Your IP address wasn't found on any of the block lists selected.
       
      Additional Details
       
      Test Steps
      Performing Sender ID validation.
       Sender ID validation was performed successfully.
       
      Additional Details
       
      Test Steps

Our mail server would be mail.orbuscompany.com

Thanks!
OrbusLLCAsked:
Who is Participating?

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

x
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.

AmitIT ArchitectCommented:
What is the next hop after Exchange server?
Do you have any email gateway after Exchange server?
Error clearly indicates DNS issue. Are you running Exchange on VM? If yes, check VLAN configuration also.
tmoore1962Commented:
are your two internet connections in fail over or load balance.  Are the IP addresses for both ISP listed in MX record with the correct priority if they're failover?  You would also probably have to have them configured in the spf record as well for testing remove one of the internet connections (esp if not listed on mx records)
AmitIT ArchitectCommented:
Focus on next hop, sometime ISP changes IP's without updating customer. Ask your ISP.
The 7 Worst Nightmares of a Sysadmin

Fear not! To defend your business’ IT systems we’re going to shine a light on the seven most sinister terrors that haunt sysadmins. That way you can be sure there’s nothing in your stack waiting to go bump in the night.

OrbusLLCAuthor Commented:
We are using Postini right now as the in between. I have all IP's in the SPF and the circuits are failover using DNS Made Easy.
AmitIT ArchitectCommented:
then focus on postini. restart postini and check again.
OrbusLLCAuthor Commented:
Postini is a spam service in the cloud provided by Google.
AmitIT ArchitectCommented:
then call Google and tell them about this issue you are facing. Before that you can do nslookup for you Exchange server ip's as well. just to check, if DNS records for Exchange server exist properly or not.
OrbusLLCAuthor Commented:
Looks like it has to do with our Sonicwall and DNS. I have the DNS record set for 40.141.69.67, but the mailserver is showing the IP as 40.141.69.66 which is causing issues. Can someone guide me into making the correct NAT entry on the Sonicwall?
AmitIT ArchitectCommented:
As I said it is a DNS issue. I also mentioned to focus on next hop, which is Sonicwall in your case. For sonic wall create a new question.

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
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
Exchange

From novice to tech pro — start learning today.