I don't think that's possible, because there aren't any such granular settings.
As far as I know, this can't be done with MS Exchange/MS365 either...
Gabriele Maoret - Head of SysAdmins and CISO at SERSIS
Currently manages 6 SmarterMail installations (1 in the cloud for SERSIS which provides services to a few hundred third-party email domains + 5 on-premise for customers who prefer to have their mail server in-house)