Is it permissible to speak with non-Muslims (males and females) online with words that please Allah?

If the purpose of the speech that pleases Allah is to invite disbelievers to Islam, then it is one of the best deeds. The invitation should be from men to men, and from women to women. As for mere chatting with them, it is not advisable because a person is influenced by their friends, and will be with those they loved on the Day of Judgment. If the conversation is between men and women, then it is obligatory to avoid it unless it is for inviting them to Islam, and this should be done through one's wife or one of the maharim (unmarriageable kin), due to the temptation of women, against which the Prophet, peace and blessings be upon him, warned.