you have already implemented it here... Very nice!

Here is a quick test implementation: my_little_forum_2.1_code_extension.zip

See also for a suggestion at the end of this post.

OK but what exactly do you hope to achieve by this? You're right that it isn't really necessary that the user contact forms are indexed by search engines. But the admin contact form should be, shouldn't it?

Testing the link, I discovered another difference in behaviour of v2 to v1. In the old forum an internal link with the 'msg=' BBCode opened the post according to the user’s preferences (thread/mix/board). Here the post is always opened in thread-mode (or whatever the correct term is). Bug or feature?

I would call it a "historical problem". From version 2 on I really wanted to get rid of these confusing "views". However, finally the "Table view" survived which is actually a crossover between the old "Board view" and "Mix view". From this view the postings are opened in the "complete thread" mode. This behavior isn't really logically explainable! Furthermore, no individual parsing of the postings is done anymore (performance optimization) which makes it impossible varying the links for each user.

Alex