We are constantly getting the error when our mail servers try to connect:
451 4.4.0 Primary target IP address responded with: “421 4.2.1 Unable to connect.” Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.
This happens to all domain users that have an mx record or is hosted with mxlogic.net.
Our 50 person organization has issues with all the companies we do business with that have mxlogic.net, and it is a lot of recipients to communicate with, and most recipients dont have IT on staff to help them.
Is there a way for a sysadmin to contact at McAfee/MxLogic to put on a allowed sender list.
We recently switched to a new ISP.
Our static IP's are not listed on any blacklists
We have PTR records set up
Our SPF/TXT records are set up
No other domains are having issues with us.
Verified above with mxtoolbox.com (and various other domain checks)
Have tried forced HELO
Have tried connecting via TLS to those domains.
Using MS Exchange 2007 with all the latest service packs and updates.
I switch over to my old isp, and retry the queues, and it goes out with no problems.(old ip on old isp that is set to disconnect soon because we have new isp)
Any advice as to where to go from here?