In what context or situation? Please provide more information so I can give you a specific answer.
The phrase "to whom it may concern" is known as a salutation or a formal greeting used at the beginning of a letter or email when the recipient is unknown.
When the pronouns who, whom, whose, which, and that are used to introduce dependent clauses they are relative pronouns.When the pronouns who, whom, whose, and which are used to introduce a question, they are interrogative pronouns.
No. It is commonly preceded by a preposition because it is the objective form of "who." You could say "who called whom" without using a preposition.
Relative pronouns
The subject receives the action of the verb. The dog chased the cat. what was chased = the cat.
A person from Rome is called a Roman.
Amerigo Vespucci
They are called the intended recipient or the addressee.
by whom were you taught english?
Adrian Hilton
Trustworthy.A confidant is a person to whom secrets or private matters are disclosed.
The payee
her name maybe?
Samuel.
landlord
Aris Total
Iberians, after whom the peninsula is named