Nellie -- Ocado don't appear to be notifying their customers by e-mail, or if they are, it is taking a long time for the notification(s) to arrive. I am a long-standing customer, and informed them of the scam by telephone shortly after 11:12 today, but so far I have received no e-mail from them informing me of the message or of the risk of opening the attachment. They have, however, posted a warning on their web site, which reads :
Important Message
Some customers have been targeted with a spam email today which looks like it's from Ocado - the subject line is "Your receipt for today's Ocado delivery", and the delivery time is between 12pm and 2pm and the driver's name is Paul. If you have received this email please delete it without opening the attachment. Thank you.