Backup of E-mail from Iplanet Messaging Server

Our bootleneck is with E-mail backups.We are using IPLANET Messaging Service.We have a Mail Server and a Backup Mail server for DR.But backup of mail to secondary storage media for such crisis as fire,etc is not in place as backing up by Iplanet is not comprehensive and restoration method not clear.Problem like how to generate log for backups,in case of restoration of mail for a particular day of a particular mail-box,etc are there. We are using temporary method of NT backup by using 20/40 GB DLT cartridges and some in-built software as frontend but the entire process in not foolproof.Is anyone to help and guide in this issue?