Client has an existing Exchange 2007 deployment. The OWA instance is configured to only use NTLM authentication. ExRCA (http://www.testexchangeconnectivity.com) comes back clean, and I can proxy log in to any mailbox on the server.
When configuring the migration endpoint through the EAC, I would receive an error that the migration endpoint could not be discovered, even after entering the credentials, server, and RPC proxy server values manually.
SolutionThe solution ended up with my old friend PowerShell. You can create migration endpoints through it using the New-MigrationEndpoint cmdlet. The key was forcing the authentication to NTLM.
New-MigrationEndpoint -ExchangeOutlookAnywhere -Name NewEndPointName -ExchangeServer EXCHSERVER.DOMAIN.local -RpcProxyServer OWA.DOMAIN.com -Credentials (get-credential firstname.lastname@example.org) -EmailAddress email@example.com -SkipVerification -Authentication NTLM