Home

Exchange 2013 cross-forest migration to Office 365

%3CLINGO-SUB%20id%3D%22lingo-sub-312758%22%20slang%3D%22en-US%22%3EExchange%202013%20cross-forest%20migration%20to%20Office%20365%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-312758%22%20slang%3D%22en-US%22%3E%3CP%3EScenario%3A%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EI%20am%20performing%20workstation%2C%20user%2C%20and%20mailbox%20migrations%20from%20Forest%20A%20to%20Forest%20B%2C%20with%20a%20two%20way%20transitive%20trust%20in%20place.%20Forest%20A%20has%20Exchange%202013%20and%20Forest%20B%20has%20Office%20365%20(with%20an%20Exchange%202016%20server%20for%20management%20purposes%2C%20with%20Azure%20AD%20sync%20in%20place).%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EOn%20Forest%20A's%20Exchange%202013%20server%2C%20I%20am%20doing%20remote-moves%20to%20Forest%20B's%20Office%20365%20tenant%20in%20parallel%20to%20the%20Active%20Directory%20user%2Fworkstation%20cutover.%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EAfter%20the%20workstation%20and%20mailbox%20have%20been%20cutover%20to%20Forest%20B%20%2F%20Office%20365%20and%20the%20user%20logs%20in%20for%20the%20first%20time%20-%20Outlook%20always%20tries%20to%20connect%20to%20Forest%20A's%20CAS%20server%2C%20no%20matter%20what.%20This%20results%20in%20repeated%20credential%20prompts%2C%20and%20no%20acceptance%20of%20either%20legacy%20or%20new%20credentials.%20I%20have%20updated%20the%20SCP%20object%20to%20outlook.office.com%20and%20autodiscover%20seems%20to%20be%20taking%20the%20logical%20steps%20with%20'test-email%20autoconfiguration'%2C%20but%20there%20seems%20to%20be%20no%20re-direction%20from%20the%20legacy%20CAS%20server%20to%20Forest%20B's%20Office%20365%20tenant.%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EI%20am%20lost%20here%2C%20what%20am%20I%20overlooking%3F%20Is%20there%20some%20additional%20attribute%20I%20need%20to%20set%20in%20the%20source%20forest%20to%20get%20the%20redirection%20to%20Office%20365%20(%20I%20have%20already%20set%20the%20targetaddress%20attribute)%3F%20There%20are%20some%20instances%20where%20if%20I%20cancel%20the%20first%20credential%20prompt%20(i.e.%20the%20connection%20to%20the%20legacy%20CAS%20server)%2C%20autodiscovery%26nbsp%3Bwill%20kick%20in%20and%20open%20a%20new%20credential%20prompt%2C%20connecting%20to%20Office%20365.%20From%20there%20I%20can%20enter%20my%20credentials%20and%20it%20works%20as%20expected.%20Any%20help%20here%20is%20appreciated.%20I%20hope%20I%20don't%20need%20to%20recreate%20outlook%20profiles%20for%2010K%2B%20users....%3C%2FP%3E%3C%2FLINGO-BODY%3E%3CLINGO-LABS%20id%3D%22lingo-labs-312758%22%20slang%3D%22en-US%22%3E%3CLINGO-LABEL%3EExchange%20Online%3C%2FLINGO-LABEL%3E%3CLINGO-LABEL%3EExchange%20Server%3C%2FLINGO-LABEL%3E%3C%2FLINGO-LABS%3E%3CLINGO-SUB%20id%3D%22lingo-sub-661314%22%20slang%3D%22en-US%22%3ERe%3A%20Exchange%202013%20cross-forest%20migration%20to%20Office%20365%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-661314%22%20slang%3D%22en-US%22%3E%3CP%3E%3CA%20href%3D%22https%3A%2F%2Ftechcommunity.microsoft.com%2Ft5%2Fuser%2Fviewprofilepage%2Fuser-id%2F178797%22%20target%3D%22_blank%22%3E%40David%20Mollin%3C%2FA%3E%26nbsp%3B%3CBR%20%2F%3E%3CBR%20%2F%3EHi%2C%3CBR%20%2F%3E%3CBR%20%2F%3EI%20was%20wondering%20what%20was%20the%20solution%20to%20your%20problem%20if%20you%20have%20discovered%20it%3F%3CBR%20%2F%3E%3CBR%20%2F%3E%3C%2FP%3E%3C%2FLINGO-BODY%3E
Highlighted
David Mollin
New Contributor

Scenario:

 

I am performing workstation, user, and mailbox migrations from Forest A to Forest B, with a two way transitive trust in place. Forest A has Exchange 2013 and Forest B has Office 365 (with an Exchange 2016 server for management purposes, with Azure AD sync in place).

 

On Forest A's Exchange 2013 server, I am doing remote-moves to Forest B's Office 365 tenant in parallel to the Active Directory user/workstation cutover.

 

After the workstation and mailbox have been cutover to Forest B / Office 365 and the user logs in for the first time - Outlook always tries to connect to Forest A's CAS server, no matter what. This results in repeated credential prompts, and no acceptance of either legacy or new credentials. I have updated the SCP object to outlook.office.com and autodiscover seems to be taking the logical steps with 'test-email autoconfiguration', but there seems to be no re-direction from the legacy CAS server to Forest B's Office 365 tenant.

 

I am lost here, what am I overlooking? Is there some additional attribute I need to set in the source forest to get the redirection to Office 365 ( I have already set the targetaddress attribute)? There are some instances where if I cancel the first credential prompt (i.e. the connection to the legacy CAS server), autodiscovery will kick in and open a new credential prompt, connecting to Office 365. From there I can enter my credentials and it works as expected. Any help here is appreciated. I hope I don't need to recreate outlook profiles for 10K+ users....

1 Reply

@David Mollin 

Hi,

I was wondering what was the solution to your problem if you have discovered it?

Related Conversations
Tabs and Dark Mode
cjc2112 in Discussions on
22 Replies
Stable version of Edge insider browser
HotCakeX in Discussions on
35 Replies
flashing a white screen while open new tab
cntvertex in Discussions on
13 Replies
How to Prevent Teams from Auto-Launch
chenrylee in Microsoft Teams on
28 Replies