On this question, let me cite her one of my earlier answers:

 

Chatting with members of opposite sex, whether they are Muslims or non-Muslims, personally face to face, or on phone or chat lines all fall in the same category. The haram of it is haram, and the halal of it is halal.

Islam does not allow Muslims to be befriending members of opposite sex for sake of companionship or for casual conversations; it has been forbidden because of its risks; it may entail isolation, lead to unlawful flirting, and engender unlawful thoughts, desires or lusts.

However, occasional, serious, business- like conversations with the members of the opposite sex are considered lawful just as they are lawful when done face to face so long as one observes the Islamic ethics of interaction.

Islam teaches that as Muslims we must shun not only that which is clearly haram but also everything that creates agitation or doubt or restlessness in our souls: The Prophet, peace be upon him, said: “Sin is that which causes agitation in your heart/mind; whereas virtue that which the heart is content and at peace about it!”

So engaging in unnecessary chatting may lead to unforeseen consequences; it may also engender doubts and suspicions in our minds as well in the minds of others; so we are best advised to shun them altogether in the first place in order to safeguard our religion and honor. The Prophet, peace be upon him, said: “Halaal is clear; Haraam is clear, but there are certain cases which are dubious or doubtful; whoever shuns them he safeguards his religion and honor; whoever falls into t hem, he risks falling into haraam like a shepherd who lets herd graze around the forbidden territory; for it may thus encroach upon the forbidden territory!”

 

Almighty Allah knows best.