Never post chain letters, and it is strongly advisable not to post virus warnings, as most are hoaxes. If you are going to post something with an explicit erotic content, please include a warning in beginning of your posting. These warnings have really been necessary a few times. Also, if you're going to include other list members in your fantasy, it's better to check with them first if your posting is going to be personal or explicit. It is up to your own judgement if you should announce the contents of your posting in the subject header or in the first line so that women who want to can skip that topic.
Postings can be in any major European language.
But really, they can be in any language, as long as there are enough of you to read them. Don't feel shy to write in German, for example, if you want to. There has been a remarkably flame free atmosphere so far. We have had some disagreements, though. In general, the attitude is that, with so many different cultures and languages on this list, one has to be lenient to postings that seem offensive at first sight.