troubleshooting Question

Exchange 2010 - Office 365 Hybrid Migration - On-Premise to O365 not working

Avatar of Scott Townsend
Scott TownsendFlag for United States of America asked on
Microsoft OfficeExchangeMicrosoft 365
19 Comments6 Solutions1584 ViewsLast Modified:
I read somewhere:
As for MX records, these can be pointing to Office 365 or your On Premise Exchange environment, depending on your needs. As long as the Hybrid Configuration Wizard worked correctly, mail flow should be seamless between the two systems.

All of my Internal DNS MX Records are pointing to On-Premise. All of the Public DNS MX records are pointing to Office365.

Mail from O365 to On-Prem is fine.
Mail from On-Prem to O365 is stuck in the Queue for the Domain.
Error: 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.

Mail to: is getting sent to mail queue. is the Primary O365 domain.

Here is the results of: get-hybridconfiguration | fl

[PS] C:\Windows\system32>get-hybridconfiguration | fl

RunspaceId                      : de34fead-a695-444b-44e7-44cc4444becb
ClientAccessServers             : {}
TransportServers                : {VSVR-EXCH2010}
SecureMailCertificateThumbprint : 4491AE94D3444C229CBCE4439CDF1444CCB44C244
OnPremisesSmartHost             : mail.<domain-0>.com
Domains                         : {,,,}
Features                        : {FreeBusy, MoveMailbox, Mailtips, MessageTracking, OwaRedirection, OnlineArchive, SecureMail}
ExternalIPAddresses             : {<pub IP Address>}
AdminDisplayName                :
ExchangeVersion                 : 0.10 (
Name                            : Hybrid Configuration
DistinguishedName               : CN=Hybrid Configuration,CN=Hybrid Configuration,CN=myenm,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=domain-0,DC=com
Identity                        : Hybrid Configuration
Guid                            : 3d96cf44-6f44-4744-a044-dd83e946c344
ObjectCategory                  :
ObjectClass                     : {top, msExchCoexistenceRelationship}
WhenChanged                     : 1/5/2018 5:17:03 PM
WhenCreated                     : 12/7/2017 12:12:37 PM
WhenChangedUTC                  : 1/6/2018 1:17:03 AM
WhenCreatedUTC                  : 12/7/2017 8:12:37 PM
OrganizationId                  :
OriginatingServer               : ADDC.domain-o.COM
IsValid                         : True
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