Hi,
if you want to archive the contents of mailboxes over a certain age then this is done in Outlook, using the autoarchive feature. I personally do not like it, as it puts the pst files it generates deep in the user profile. If your PC hard drive dies then you have lost the archive.
One possibility is to install outlook onto your server. Assign the required permissions to allow the admin account to login to the mailbox. Then run the archive routine from there, but do it to a location that is backed up. I do this, but then archive the pst files onto DVDs.
If you need to open a pst file on a DVD you have to copy it to a hard drive first, as outlook requires read and write access to the files it opens.
Hope this helps,
Ady