Currently you'll have to login to unsubscribe.
And it's much more easier to click on "Spam" icon in gmail
than unsubscribe. I haven't done it yet, because my previous feature
request got implemented almost immediately. But not everybody may
be as happy.
And from lurker viewpoint:
On following page: https://community.qualys.com/user-notification-preferences%21input.jspa
"Send me an email summary:" could be somewhat higher or otherwise more noticeable.