The message looks like the boilerplate text for SpamAssassin, yes. One thing that SA does in addition to that is it includes headers that can be matched on by email software so that it can be handled automatically (moved to a folder, marked as read, deleting outright, etc). At the moment, though, the easiest way to tell this is a SA message is by the boilerplate text.

If we do do this, it'd be nice to note the headers that can be filtered on in a related FAQ, and to include the FAQ link in the text too.