When a call is received and transferred to another agent or queue that is unreachable, the voicemail notification (email) is sent to the address of the agent who received the call.

Here is the issue:
If your reception department receives a call that is transferred to your support department, the caller reaches the voicemail of the reception department.

Ideally, the agent or queue that is unreachable would receive the voicemail, not the agent that transferred the call.