Normally this isn't a huge problem, but this time it contained the results of a blood test which might relate to cancer.
My initial belief was that it had been sent to the wrong person by someone typing in the wrong address, and I managed contact someone at the testing company and ask them to get it to the right person by another route, so hopefully that side of it is sorted.
But it's become apparent that something glitched and mail sent to email@example.com was instead sent to me. I'm not sure if this was a one-off fluke or if it's happened before - I think in previous instances the sender has used the wrong address, but I may have missed others where this problem occurred.
Can anyone suggest a good route for reporting this to Google that won't require me to send them the original - confidential - message which is now permanently deleted?
later - as pointed out in comments, this has happened because firstname.lastname@example.org is also my proper email address, a dot anywhere in the first part makes no difference, and the address in the initial email should have been something else - presumably xxxxxyyyyy2 or something of the sort.