Asalam A'lakum Warakmatulah Wabarkatuh. I have a question saying the full asalam alaykum on this forum or any forum give us rewards for saying it as saying it to a live person.
"And when you are greeted with a greeting, greet in return with what is better than it, or (at least) return it equally."
[4:86]
"....But when you enter houses, greet one another with a greeting from Allah, blessed and good...."
[24:61]
There are also hadiths on it:
In one Hadith a man asked the Prophet about which aspect of Islam was best. The Prophet replied:
"Feeding the hungry, and saying salaam to those you know and those you don't know." (Bukhari and Muslim)
"The person closest to Allah is the one who precedes others in greeting." (Abu Dawud)
Well you obviously have to mean what you are saying, you obviously have to have the intention of greeting, and in Islam that is wishing peace (assalamu aleykum), possibly extending to mercy of Allah (wa rahmat Allahi), and even to the blessings of Allah (wa barakatu).