that is a false statement. the mailbox does not simply get purged periodically. items are methodically deleted one at a time from oldest to newest after 20 items have been exceeded, and as each new item is added, but items are not removed if the mailbox is not full.

No it is very true. The mailboxes, whether by an act of Bungie intentionally or not, occasionally DO get purged. Yes you are correct about the rotation of the equipment that is 'stored' there but there have been MULTIPLE instances of complete mailbox purges hence Bungie advising in a weekly update in the past that the postmaster is NOT a place to store gear and that it is NOT additional vault space. A lot of the times purges have happened were immediately following a major update which probably is sync problems between tables in the databases but it DOES happen.

i don't buy that, since my mailbox frequently contains items and has never been purged, and i've been playing since the alpha. in this case, only the ghost was missing and other acquired items were still in the mailbox. bungie recommending against using the mailbox for storage has more to do with the potential to lose items as the mailbox overflows than suggesting they occasionally wipe mailboxes, which is not substantiated by your references to weekly updates.