Q: What does “was-salaam” mean? Is it Sunnah to end a letter with these words? Is it compulsory for the person who receives a letter which ends with “was-salaam” to audibly reply with wa alaykum salaam?
A: A letter is a meeting, and a meeting starts with salaam and ends with salaam.
It does not have to be audible. He can say it softly.
And Allah Ta’ala (الله تعالى) knows best.