The manuals are not very clear about the Exchange archive expiry.
I found this about Storage Expiry for FSA on page 146 of the Setting up File System Archiving document:
About scheduling storage expiry for FSA
When an item's retention period expires, File System Archiving can automatically
delete it. File System Archiving does this according to the schedule that you define
with the Administration Console, on the Storage Expiry tab of the site Properties
dialog box.
File System Archiving does not delete archived items when either of the following
conditions applies:
■ On the "Storage Expiry" tab of the site Properties dialog box, the schedule is
set to "Never" or you have checked "Run in report mode".
■ On the "Advanced" tab of the Archive Properties dialog box, "Delete expired
items from this archive automatically" is unchecked.
If this is true about FSA, is it not also true about Exchange Archiving? If Storage Expiry is configured and scheduled on the site, expired Exchange items would be deleted UNLESS that specific archive has the "Delete expired items from this archive automatically" option unchecked?