I just wanted to bump this again and see if I could get anyone else to try to get external scripts via the Linux client working, or at least verify my problem with a test run of external scripts. LVM backups are SAAH-WEET! I am manually creating an LVM snapshot, running a backup via the Linux client, and then removing the snapshot. So far my experience with this performance-wise is very good. The only thing I am missing is automation. Downtime for the mail server amounts to 2min - tops, which is the amount of time it takes to stop and start all the mail server processes. The snapshot is darn near instantaneous. Once I can get Retrospect to create and remove the snapshot, I will have an awesome backup solution.