No, they used the email from the institute they worked at when the produced the paper. They're no longer at that institute, and that email no longer exists (wh

No, they used the email from the institute they worked at when the produced the paper. They're no longer at that institute, and that email no longer exists (while some institutions give some leeway, I know of at least one major university which removes them the day the contract ends). This is a common problem if you're providing services to academics and you've tied yourself to using emails as identifiers.