as-salam 3alaykom.
my question is concerning answering salam but in e-mail. i subscribed to a daily hadeeth (imaam al-Bukhari) and with each sent mail there's a salam to all the group. since we r obliged to answer a salam, is it an obligation on us to reply back with an e-mail or it's enough to say in urself the reply intending salam on these ppl who have sent the mail. Some ppl asked not to send salam for they r obliged to reply and they are too busy to reply every day, but at the same time it's an obligation to greet muslims on seeing them, right? And as u stated a hadeeth in 1 of ur fatwa: The better amongst the two is the one who starts greeting the other with Salaam.” What's the right thing to do in this case?
Jazakum ALLAH khairan. Fee aman ALLAH

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Initiating the greeting of Salaam is recommended not obligatory, and it is one of the causes of spreading love among the Muslims. However, answering Salaam is a collective duty as we explained in Fatwa 85077.

Whoever receives a letter starting with Salaam, he must answer it (to himself) as stated by An-Nawawi in his book “Al-Athkaar”. Nonetheless, it is not obligatory on you to answer in writing even if that letter was sent exclusively to you, not to mention the emails that are sent to many people all over the world as is the case in question.

Allaah Knows best.