Mallin!!!! (Site help too please!)

Can any of the moderators help please? I've received a PM to my email inbox from one of the good people on this site, and have tried to reply, but it comes back as undeliverable. I've had this happen before, does anyone know why and how I can remedy it? I'd hate the writer to think I was not replying.....

Clare, have you got my personal e-mail address , I think I have yours somewhere is it the same. Linda

Thanks! I'm still at a loss to know why I can't reply though. How truly bizarre.