Right before the delivery, hyperlink tags are processed and replaced with the proper values depending on the message format. If the message is a 'Plain Text' message the hyperlink tags are simply replaced by their corresponding URLs. If the message is a 'Styled Text' message a rich HTML hyperlink is created using the assigned tag name as the clickable text but hiding the URL. For example, you would get Maxprog rather than www.maxprog.com/.
You can access the Hyperlink Manager selecting the 'Edit | Insert Hyperlink | Edit' menu. The URL has to begin with 'http://' for a web page, 'https://' for a secure web page, 'ftp://' for a FTP address or 'mailto:' for an email address. The Hyperlink Manager shows you whether your URL is valid or not by coloring the text in blue if valid or in red if otherwise. Note that when using the 'Styled Text' format you can add an hyperlink to the manager just highlighting some text on your message and selecting the 'Message | Link to URL' menu. You will be asked for the hyperlink URL and the highlighted text will be used as the tag text.