He speaks improperly with a woman, with the excuse that he is teaching her

I am a girl who has been on the Internet for a short time, but I have noticed that some people are very confused and they mix truth with falsehood. From the way some of them speak, they appear to be good and pious, but some of the things they do are very strange.
 When I first starting going on the Internet, some of the sites I went to were chat rooms. I admit that this was a mistake on my part, but I have put matters right, alhamdu-Lillaah. I stopped going into chat rooms two weeks after I started. But whilst I was visiting chat rooms I got to know a man who, from what he says, appears to be righteous and pious, and keen to pursue good. He tries to put right whatever he can, and he sends out letters containing words of religious exhortation by e-mail to everyone he knows. He goes into chat rooms on the basis of the belief and principle that he adheres to, which is that good people should be present in these sites, in which there are a lot of bad people, in order to crowd out the bad people.
 The main thing is that I stopped going to the chat rooms, but I continued to communicate with him by e-mail. He was trying to persuade me that I had to go to the chat rooms in order to reform the women, because women are closer to other women, especially on sites where there are so many women that the “wolves” are tempted to come and “hunt” them. I did not respond to his request because I knew how damaging it is to go to those sites where the evil outweighs the good. The way he spoke to me in his letters was very respectful and he was very selective in the words he chose; I was equally careful in the way I spoke to him. This encouraged me to ask him to teach me the basics of the Internet via e-mail, or, if that was not possible, via “messenger”. He agreed to do that via “messenger” so we started the lessons, and he carried on being respectful and serious. But I noticed that sometimes he would joke or get carried away in talking about matters that had nothing to do with the lesson, which he called educational topics. And he also asked about some personal matters such as the city where I live, etc. I knew that he was in touch with a group of women with whom he discussed educational matters and the state of the Muslims, etc., and that these discussions might go on for hours. I did not like this state of affairs and I told him that frankly. I also told him that this joking was not permitted, and that he should be formal when speaking with women, and not use certain phrases. He quoted as evidence that it is permissible to speak with women the fact that the shaykhs answer questions from women; and he quoted as evidence that it is permissible to joke the hadeeth “No old women will enter Paradise” – meaning that the Prophet SAWS (peace and blessings of Allaah be upon him) was joking with that old woman when he said that to her. He said that being too formal and reserved may lead to the opposite result. I was not convinced by his arguments, because from the little knowledge that I have, this is not permitted. I asked him to complete the lessons via e-mail and not to use the “messenger”, and until now he has not replied at all. I find it strange and wonder how he could do that when he has reached such a high level of knowledge and religious commitment, as well as being haafiz al-Qur’aan (i.e., he has memorized the Qur’aan by heart). I want to point out that this is a subtle trap that is one of the snares of the Shaytaan, by means of which he confuses people. What is the final word on this problem? Please excuse me for writing such a long question. May Allaah reward you with good.