You're right I agree with you.
I'll advise my customer to upgrade his mail server.
One more question :
- BES server is on another Domino Domain (BES/XXX
_FR) than mail server (MAIL/SVR/XXX), communication are made with cross certificate, and they communicate well between eachother.
But : BES is not on the "localdomainserver" in the mail server, Domino admins add BES server in ACL with Manager rights (and delete), are you thinking it could cause problems ?