I am able to post my messages with HTML formatting. Many of us use simple text-based programs to read news, and posts with HTML formatting can be very difficult to read. For some newsreaders, you will need to change more than one setting to completely eliminate this behavior. Feel free to post any corrections or differences in opinion that you feel are necessary. Feel free to indicate that you are hurt, unhappy, or insulted because of their comments.
People are usually fairly good at recognizing when someone is being terribly unfair.
Yes, it is undoubtedly your right to flame if you want to, but the vast majority of the group would be happier if you did not. Maybe they only meant to tease you, not realizing that you would really be insulted. Assuming the worst is a depressing way to live one's life. One of the best places to start has always been the newsgroup news.announce.newusers . This group is home to a wide range of articles that provide introductory information about many aspects of Usenet news.