Provavelmente, você ainda tem um registro do AD que direciona os clientes para o Exchange local durante a descoberta automática.
As etapas para resolver isso podem ser encontradas no excelente artigo .
You can also delete the SCP record altogether using ASDI edit:
- Select the “Configuration” naming context
- Drill down to:
CN=Services\
CN=Microsoft Exchange\
CN=Your Org name\
CN=Administrative Groups\
CN=Exchange Administrative Groups\
CN=Servers\
CN=Your Server Name\
CN=Protcols\
CN=Autodiscover\- And delete the CN=Your Server Name of class serviceConnectionPoint in there