Replying to Slmz?

Question: Should I reply with the Sunnah Salaam of walaikumussalaam Warahmatullaahi Wabarakaatuh to a message which begins with Slmz?

Answer: Slmz, Aslm, Aslamz, Salaam, Slm, Salaamz and any other funny writing is NOT a Sunnah Salaam which deserves a Waajib reply of ‘Walaikumussalaam Warahmatullaahi Wabarakaatuh’.

Writing the Sunnah Salaam in abbreviated forms show lack of sincerity in the Salaam.

Yes, when Assalaamualaikum is written in a message, then a reply is Waajib. And this reply can either be verbally or in as a reply to the message in writing.