If you mean "distrubution group" like a mail that will be reroute to every member (eg: support@domain.zxx will be routed to every single account of the members of "support"), you can use alias (in domain configuration under ACCOUNTS--> ALIASES) to do that:
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)