The past 24 hours, I noticed that I was not receiving any email messages in my Yahoo account. This coincides with Yahoo Mail upgrade.
After 'Googling', I found out that this upgrade defaults your account to forward all your incoming messages with 'Forward Only' option (go to settings>accounts>edit). Unfortunately, it used an old email address of mine which is no longer valid.
So I put in an alternate email address with 'Store and Forward' option.
So, yeah, it looks like I lost all incoming messages (including spam) the last 24 hours. Grrrr!
I'm waiting for an answer now from Yahoo's customer care. Hopefully, they can still recover it.