Q.) If somebody begins his e-mail or his SMS (text message to a phone) with “Assalamu aleikum”, will it be wajib for the recipient to reply with “wa alaikum salam”?

And what about the sender just writes “Salam” rather than “Assalamu aleikum”, will it be wajib to reply in this case?

A.) It is necessary to reply to a Salaam sent in writing by SMS etc, either by sending a response in writing or by verbalising the response when one receives the message.

And Allah Ta’ala Knows Best.