The ‘Send Message’ BBCode for URLs does not encode if the URL does not start with exactly “http:” or “https:”. The message preview is properly encoded, but the actually sent message is not.
For example, if the url starts with “HTTP:” it will not work. If the url starts with “ftp:” it will not work.
I only tested this with the BBCode syntax of [ url = xxxxxxxx] label text [ / url ]. (Note, extra spaces included here so that it will not be encoded here.