David Warren 2, You say:
"Within the EV agent almost everything backs up in a timely manner except "EV-PTN::\\%servername%\MailStore01\MailStore01 Ptn1@E:", which is the actual Vault DB. "
I think it is the actual Vault Store Partition #1 Data on the E: drive. It would say something else for SQL database.
Also SQL database is usually significantly smaller than the actual archived data and normally doesn't take a very long time to back up.
For example we have close to 40TB of archived data. Our EV SQL database total size is about 300GB.