You can use an Internet search engine to look up messages on the internet by their message Id. Select 'Find Message on Internet' in the search menu or message pane popup menu.
By default, XanaNews uses the Google Groups search engine. You can configure it to use another search engine in the Program Settings options
When you select 'Find Message on Internet', XanaNews first checks to see if a message Id is highlighted on the message pane. If it is, XanaNews searches for this message. if there is no highlighted message id, XanaNews searches for the currently selected message.
If you hold down the Ctrl key when selecting 'Find Message on Internet', a form is displayed where you can manually enter the message Id to search for.