A rather important mail sent as a reply to my mail to the person arrived in my inbox on 10 February - but I can't see it when I check my mails. I've looked in settings and in spam, and that doesn't explain anything. The mail only appeared when I searched on the person's email address. Then I could see that she had answered me, but if I just go in my inbox, the mail doesn't appear at all. I've returned to the old Yahoo version, because I didn't like Yahoo sorting my mails as to what is important and not important. So it's not because it's in the non-essential category. This is a big mistake - and it was an important message, too.