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Thanks to both. Yes, I knew that I shouldn't click on a link. However, it has shown up an interesting (to me, anyway), fact: I didn't have an Apple ID at all. I tried logging in to itunes as suggested, but couldn't do it; then discovered that I'd never signed up to Apple. I've only used itunes in the past to copy stuff from individual CDs on to the hard drive and to a composite CD, and must have succeeded in doing this without the ID. I've now done that and it all looks genuine. So the scam email has been some use.