Since my original post, I've discovered from people on another forum I use that this particular email has been doing the rounds for weeks. Despite my setting up message rules to have any emails including the words 'Asda $150 worth of shopping' in the subject line deleted, I'm still getting them. One of the people who received these emails has said she clicked the unsubscribe link at the end of the email and so far she hasn't received any more.

This is the link I received in my email:

To unlist yourself simply visit this link or http://www.fructuaries.com/?rl=xxq087069...d7bpq&qz=hr
mail us at: 2020 Pennsylvania Ave NW, #319, Washington, DC 20006

The address in Pennsylvania is one I've noticed before in other spam emails which I'd deleted in the past.