Mississippi draws its line at the bar, not the classroom
How old do I have to be to serve alcohol in Mississippi?
Eighteen to wait tables. A person at least 18 but under 21 may take orders for and deliver alcoholic beverages within the scope of employment by the holder of an on-premises retailer's permit.
Can an 18-year-old tend bar?
No. That exception expressly does not authorise anyone under 21 to tend bar or act in the capacity of a bartender. Taking a drink order at 19 is allowed; mixing or pouring it is not. Mississippi is one of the states where the two jobs are legally different jobs.
Does Mississippi mandate server training?
No. There is no statewide requirement that individual servers complete a training programme. Mississippi is a local-option state, so what varies from county to county is whether alcohol may be sold at all — not what training the seller holds.
Then what is this course for?
Employers and insurers, mostly, plus your own exposure. Without a state standard, Mississippi venues set their own, and a documented responsible-service course is the usual proof. This one covers reading an ID quickly, the tells on altered and borrowed licences, judging impairment from behaviour rather than drink count, and refusing service without a confrontation.