Unity VMs Not Been Delivered to Outlook

After investigation, there're two issues, VMs stuck in UnityMsgStoreSvc mailbox, then VMs stuck in 03-to-10 Connector.

Topology:

• UnityMsgStoreSvc mailbox resides on EXC-03
• In 03-to-10 Connector: EXC-01 was listed as the only server to be able to send emails & EXC-02 is the only Remote Bridgehead

Troubleshoots:

1. Emails queued in UnityMsgStoreSvc mailbox: the "unity_UNITY" account password must have expired. Changed the account to never expire, then emails start to empty from the mailbox.

2. However, the emails now stuck in the Connector queues on EXC-01, and unable to connect to EXC-02. Reboot EXC-02 to resolve this.