Defferred Mails

A customer had an outage on their exchange server, after solving the problem the most messages in the queue were delivered. But there are about 200 messages left in the queue with status 'Defferred'. Pressing 'Force Email Delivery' has no results. Is there a way to deliver the email?

Reply:

Deferred means that the mail server cannot connect to the recipient server and it's putting the email on hold until later when it retries. The reasons for not being able to connect to the recipient server could be: 1. Server is down 2. Your box is blocked from connecting to external systems