Exchange Point-in-Time Recovery

Controls whether Restore will delete Exchange logs to restore Exchange to a point-in-time.

Yes	DPX will delete existing transaction logs before restore and then perform a point-in-time restore, which brings the database back to the state when it was backed up. This option is commonly used when you are restoring a backup instance that is not the latest. This option is strongly recommended whenever a restore is needed to nullify an incorrect or maliciously altered transaction.
No	This is the default. DPX will not delete existing transaction logs before restore. DPX performs an up-to-the-minute restore by retaining the existing transaction logs and rolling forward all new transaction from the existing logs. This option is commonly used when you lose a database without losing its transaction logs and you choose to restore from the latest backup instance.