Many thanks to all who responded to my call for help. I think I know what happened but I don't know why. Messages ended up in the "suspected spam" folder, but it is not clear what triggered it.
Than you, Ros for the URL regarding change of email, a page that I have bookmarked. I now know not to put email addresses into G2G but I did not know it then. You learn something new every day.
Cheers to all.