SMTP Delivery failure, Source: AGENT

So I ran into an issue the other day involving emails not being delivered.. Upon further inspection I noted that the Barracuda passed the messages through because the sending domain was whitelisted.  Funny though because I was one of the recipients and the message did not come through.

We have two Exchange 2010 servers so I began inspecting the Transport logs on teh gateway server.  Turns out those messages had a status of "FAIL" due to a 'SOURCE: AGENT'.

Agents meaning Transport Agents.  Now yes, we do have a Barracuda 410 Spam Filter, but also had the Anti-Spam agents in Exch enabled.

Not knowing which one is causing this failure I started with what I would logically think was causing my issue.. Sender ID.

Then re-pushed the messages from the 'Cuda.  Checking the Transport logs again I found out they still Failed.  So making a long story short I went down the list disabling each Agent was disabled and wound up my Transport Rule Agent was the cause except none of my actual Transport Rules were affecting this particular sender, message body or content.

IDK it's weird.  But at least I got mail flowing which is the important part.