btw the same post is here No Mail from 2010 -> 2003 / 2003 -> 2010 is okay!

Domain a : admin domain
Domain b : curriculum domain

I cannot send email from a 2010 mailbox to a 2003 mailbox, it queues on the hub transport server. when i check the queue i get a "451 4.4.4 DBS Query Failed. The error was: SMTPSEND.DNS.NonExistentDomain; nonexistent domain"

what domain can it not find?

OWA is working and i can send from a 2003 mailbox to a 2010 mailbox just not vice versa. I have only moved my mailbox for testing purposes so I can get this working before migrating any other mailboxes to 2010.

OWA also correctly redirect user to 2003/2010 depending on where mailbox is hosted.

--------> Original Setup
(One Exchange Organization)
DOMAIN A:
A-EXCHANGE --> Backend 2003 Exchange Server (SMTP Mail is send here from ISP)
DOMAIN B:
B-EXCHANGE --> Backend 2003 Exchange Server
B-OWA --> Frontend 2003 Exchange Server
---> Setup Now
DOMAIN A:
A-EXCHANGE --> Backend 2003 Exchange Server (SMTP Mail is send here from ISP)
A-2010-EXCHANGE --> Client Access, Mailbox, Hub Transport | 2010 Exchange Server
DOMAIN B:
B-EXCHANGE --> Backend 2003 Exchange Server
B-OWA --> Frontend 2003 Exchange Server
B-2010-EXCHANGE --> Client Access, Mailbox | 2010 Exchange Server
B-2010-OWA --> Client Access | 2010 Exchange Server


------------------------------------------
GET-ROUTINGGROUPCONNECTOR | FL ==

RunspaceId : 1898cf51-c03d-48ff-a7d9-0c3ce1cfb969
TargetRoutingGroup : First Routing Group
Cost : 1
TargetTransportServers : {A-EXCHANGE-2003}
ExchangeLegacyDN : /o=MyOrganization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Connecti
ons/cn=A-EXCHANGE-2010-EXCHANGE
PublicFolderReferralsEnabled : True
SourceRoutingGroup : Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers : {A-EXCHANGE-2010}
HomeMTA : Microsoft MTA
HomeMtaServerId : A-EXCHANGE-2010
MaxMessageSize : unlimited
AdminDisplayName :
ExchangeVersion : 0.1 (8.0.535.0)
Name : A-EXCHANGE-2010-EXCHANGE
DistinguishedName : CN=A-MAIL-01-EXCHANGE,CN=Connections,CN=Exchange Routing Group (DWBGZMFD01QNBJR),CN=Rout
ing Groups,CN=Exchange Administrative Group (FYDIBOHF23SPDLT),CN=Administrative Groups,C
N=MyOrganization,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=a,DC=loca l
Identity : A-EXCHANGE-2010-EXCHANGE
Guid : 52a26bb0-6bd2-48ff-9d05-b0bbb00c96d6
ObjectCategory : a.local/Configuration/Schema/ms-Exch-Routing-Group-Connector
ObjectClass : {top, msExchConnector, msExchRoutingGroupConnector}
WhenChanged : 8/22/2010 7:06:00 PM
WhenCreated : 8/22/2010 7:05:38 PM
WhenChangedUTC : 8/22/2010 6:06:00 PM
WhenCreatedUTC : 8/22/2010 6:05:38 PM
OrganizationId :
OriginatingServer : a-dc2.a.local
IsValid : True

RunspaceId : 1898cf51-c03d-48ff-a7d9-0c3ce1cfb969
TargetRoutingGroup : Exchange Routing Group (DWBGZMFD01QNBJR)
Cost : 1
TargetTransportServers : {A-EXCHANGE-2010}
ExchangeLegacyDN : /o=MyOrganization/ou=First Administrative Group/cn=Configuration/cn=Connections/cn=A-EXCHANGE-2010
PublicFolderReferralsEnabled : True
SourceRoutingGroup : First Routing Group
SourceTransportServers : {B-EXCHANGE-2003}
HomeMTA : Microsoft MTA
HomeMtaServerId : EXCHANGE
MaxMessageSize : unlimited
AdminDisplayName :
ExchangeVersion : 0.1 (8.0.535.0)
Name : EXCHANGE-A-EXCHANGE-2010
DistinguishedName : CN=EXCHANGE-A-EXCHANGE-2010,CN=Connections,CN=First Routing Group,CN=Routing Groups,CN=First A
dministrative Group,CN=Administrative Groups,CN=MyOrganization,CN=Microsoft Exchange,CN=Services,
CN=Configuration,DC=a,DC=local
Identity : EXCHANGE-A-EXCHANGE-2010
Guid : 77084dd0-7987-46dc-a171-c00eeb1e45f2
ObjectCategory : a.local/Configuration/Schema/ms-Exch-Routing-Group-Connector
ObjectClass : {top, msExchConnector, msExchRoutingGroupConnector}
WhenChanged : 8/22/2010 7:06:00 PM
WhenCreated : 8/22/2010 7:05:39 PM
WhenChangedUTC : 8/22/2010 6:06:00 PM
WhenCreatedUTC : 8/22/2010 6:05:39 PM
OrganizationId :
OriginatingServer : a-dc2.a.local
IsValid : True

RunspaceId : 1898cf51-c03d-48ff-a7d9-0c3ce1cfb969
TargetRoutingGroup : First Routing Group
Cost : 100
TargetTransportServers : {A-EXCHANGE-2003, B-EXCHANGE-2003}
ExchangeLegacyDN : /o=MyOrganization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Connecti
ons/cn=Interop RGC
PublicFolderReferralsEnabled : True
SourceRoutingGroup : Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers : {A-EXCHANGE-2010}
HomeMTA : Microsoft MTA
HomeMtaServerId : A-EXCHANGE-2010
MaxMessageSize : unlimited
AdminDisplayName :
ExchangeVersion : 0.1 (8.0.535.0)
Name : Interop RGC
DistinguishedName : CN=Interop RGC,CN=Connections,CN=Exchange Routing Group (DWBGZMFD01QNBJR),CN=Routing Gro
ups,CN=Exchange Administrative Group (FYDIBOHF23SPDLT),CN=Administrative Groups,CN=MyOrganization
,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=a,DC=loca l
Identity : Interop RGC
Guid : 709716c6-d556-465e-b74a-9c178c9f756a
ObjectCategory : a.local/Configuration/Schema/ms-Exch-Routing-Group-Connector
ObjectClass : {top, msExchConnector, msExchRoutingGroupConnector}
WhenChanged : 8/24/2010 7:00:43 PM
WhenCreated : 8/24/2010 7:00:43 PM
WhenChangedUTC : 8/24/2010 6:00:43 PM
WhenCreatedUTC : 8/24/2010 6:00:43 PM
OrganizationId :
OriginatingServer : a-dc2.a.local
IsValid : True

RunspaceId : 1898cf51-c03d-48ff-a7d9-0c3ce1cfb969
TargetRoutingGroup : Exchange Routing Group (DWBGZMFD01QNBJR)
Cost : 100
TargetTransportServers : {A-EXCHANGE-2010}
ExchangeLegacyDN : /o=MyOrganization/ou=First Administrative Group/cn=Configuration/cn=Connections/cn=Interop RGC
PublicFolderReferralsEnabled : True
SourceRoutingGroup : First Routing Group
SourceTransportServers : {A-EXCHANGE-2003, B-EXCHANGE-2003}
HomeMTA : Microsoft MTA
HomeMtaServerId : A-EXCHANGE-2003
MaxMessageSize : unlimited
AdminDisplayName :
ExchangeVersion : 0.1 (8.0.535.0)
Name : Interop RGC
DistinguishedName : CN=Interop RGC,CN=Connections,CN=First Routing Group,CN=Routing Groups,CN=First Administ
rative Group,CN=Administrative Groups,CN=MyOrganization,CN=Microsoft Exchange,CN=Services,CN=Conf
iguration,DC=a,DC=local
Identity : Interop RGC
Guid : a5796a3c-2ec2-46fc-9daa-9ebbdc68d754
ObjectCategory : a.local/Configuration/Schema/ms-Exch-Routing-Group-Connector
ObjectClass : {top, msExchConnector, msExchRoutingGroupConnector}
WhenChanged : 8/24/2010 7:00:43 PM
WhenCreated : 8/24/2010 7:00:43 PM
WhenChangedUTC : 8/24/2010 6:00:43 PM
WhenCreatedUTC : 8/24/2010 6:00:43 PM
OrganizationId :
OriginatingServer : a-dc2.a.local
IsValid : True