I'm having trouble sending emails from my on-premises exchange server to a cloud based user. Messages are being sent from my Exchange 2003 server and are getting stuck on the Exchange 2010 hybrid server with the Hub Transport Role installed. The message will sit in the "dnsconnectordelivery" queue and won't go anywhere.
I can send emails from the cloud based mailbox to an on-premises mailbox, but have the above issue when replying.
I've gone throught the deployment assistant a few times and I am trying to accomplish the following:
1. Staged migration from existing exchange 2003 server to Exchnage Online cloud-based service
2. I do not require SSO
3. All inbound mail for both on-premises and exchange online mailboxes is routed through my on-premises organization
4. All mail between on-premises and exchnage online will be routed via a Hybrid Hub Transport server
5. All mail sent to external recipients from Exchange Online mailboxes will be routed directly to the internet
I'm wondering if this could be an issue with the Exchange Certificates used on both hybrid servers (the deployment assistant is lacking some explanation and seems to contradict itselt).