Looking for Mailgate configuration help

New to RT…relatively new to Centos. Have an RT 4.4.4 install working on Centos 7.x
Have authentication working with Shibboleth, and have Queues created/permissions set. Need to get inbound email and outbound email working. Outbound will go to in house MTA.Would like to have custom aliases for inbound to queues so as an example, if one of my queues is Helpdesk, then I need to have an alias of helpdesk@rt.mydomain. Not the foggiest where to go from here!