Since yesterday (June 11), we have been having problem sending emails to Yahoo IDs. The emails would bounced back a couple hours later "A problem occurred during the delivery of this message. Please try to resend it later. The following organization rejected your message: mta7.am0.yahoodns.net (220.127.116.11)." Without any further details we don't know why the emails are rejected. We checked our company IP and they are not blacklisted. Just now when I tried to contact Yahoo postmaster, it kept saying "This page isn’t working io.help.yahoo.com is currently unable to handle this request. HTTP ERROR 500".