The Qur’an encourages us to exchange greetings among men towards men and women towards women. Thus, we find Allah says: [When you are greeted with a greeting, greet in return with what is better than it, or (at least) return it equally. Certainly, Allah is Ever a Careful Account Taker of all things.] (al-Nisa’4:86). Allah has commanded us to spread the greeting of salaam, and has enjoined us to return the greeting to all Muslims. He has made the greeting of salaam one of the things that spread love among the believers.
And it was narrated that Abu Hurayrah said: The Messenger of Allah (peace and blessings be upon him) said: “You will not enter Paradise until you (truly) believe, and you will not (truly) believe until you love one another. Shall I not tell you something which, if you do it, you will love one another? Spread the greeting of salaam amongst yourselves.” Narrated by Muslim
The command to spread the greeting of salaam is general and applies to all the believers. It includes men greeting men and women greeting women, and a man greeting his female mahrams. All of them are enjoined to initiate the greeting of salaam, and the other is obliged to return the greeting.
The eminent Muslim scholar Sheikh `Abdel Khaliq Hasan Ash-Shareef, comments: “There is no problem if a Muslim male great a Muslim female and vice verse.” In conclusion, there will be no harm if greetings could be exchanged but within the Islamic rules and this permission must not be misused.