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Level 7

Trouble with Email being sent to organizations that are hosted with (mx records)

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

We have submitted to and to with a response that says to contact the recipient.  (Dead End)

Our 50 person organization has issues with all the companies we do business with that have, 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 (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?

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