I have just installed Exchange 2010 in my domain that already has an Exchange 2007 server. I moved a testing mailbox to the new 2010 server and now cannot send mail from the testing user to another user on the old Exchange 2007 server. However, I can send from the 2007 server to the testing user on the 2010 server. I get the error about Exchange server auth not working. On the client and default receive connectors on each server I have "exchange server auth", "integrated windows auth" and TLS enabled in the authentication tab and I have "exchange servers" enabled in the permission groups tab. What else am I missing?

Hi, "Authentication" should be "Integrated Windows Authentication"Regards from www.windowsadmin.info

"Integrated Windows Authentication" is checked on all receive connectors.

Hi, Do you have Edge server in the organization? Regards from www.windowsadmin.info

No. Just HT, Mailbox, CAS.

Could you please try this : Be ensure that Transport Layer Security (TLS) check box and the Exchange Server authentication check box are only enabled and uncheck all othersRegards from www.windowsadmin.info

That worked. Thanks partner.