How to pronounce whom:
(interrogative) what person or people; which person or people.
(relative) used to refer to a previously mentioned person or people.
Example: "He's a person with whom i work. (defining)"
(fused relative, archaic outside set patterns) the person(s) whom; whomever.
Example: "To whom it may concern, all business of john smith ltd. has now been transferred to floggitt & runne."