Messages stuck in Exchange 2007 queue

Hello,

We have Exchange 2007 running on Windows 2K8 R2 that is running solely to send daily report emails from application servers (Network monitoring, Backup, etc). After a scheduled full power outage these emails are now piling up in the message queue with the Last Error 400 4.4.7 Message delayed". Filtering Event logs to the MSExchange Transport source shows the 6 days since the power outage filled with Event ID 1000 'The service is trying to start'.

After this service finally started, the logs then show Event ID 5006, 5008, 5009 and 5026 Routing warnings. The next day Event ID 12014 began showing up; referencing a missing certificate and an inability to "...support the STARTTLS SMTP verb for the connector Barracuda DHHQ SMTP1 with a FQDN parameter of xxxxxxxx.xxxxxxxx.dom"

This transport server is for outbound mail only. Our organization has email service through a different cluster but our internal monitoring applications use this local Exchange server to send daily report messages. No inbound mail comes to it. I believe it still sends mail through a Barracuda filtering device; I do not yet have access to it yet but I'm wondering if there's anything on the Exchange side that is behind these messages no longer flowing. Thanks!