I have finally found the source of the client-initiated compact requests to the mail server - Scheduled program documents in the client's Personal Address Book (see the "($Programs)" View).
Argh! Lotus/IRIS, why, why, why? I can understand the logic in wanting to compact a mail file after some data has been archived from it, but . . . You give us the feature to schedule archiving on ALL clients and this will result in ALL clients asking their mail server to compact their mail file . . . On a network where all PC's clocks are synchronised this effectively results in a DoS attack on the mail server.
Administrators schedule compact to run out-of-hours with server program documents, so having the client request a mail file compact when running the scheduled archive is just a PITA.
Rant over! :o) It sounds like this is fixed in R6.5.5 ( http://www-10.lotus.com/ldd/r5fixlist.nsf/PublicTech/5F166A44EE743B2C852570E4001BAF31?OpenDocument
), but I'm not upgrading our company just for this - I can write some code to delete the client program documents that invoke compact on the server and put this in our mail file OnOpen event - I'll post it here when tested.