T=remote_smtp defer: retry time not reached for any host

If you get this error when you are trying to send email to Yahoo. It is very likely that your server ip is black-listed.

You can contact yahoo postmaster by filling in the form here: http://help.yahoo.com/l/us/yahoo/mail/postmaster/errors/?referrer=blog.my-helper.com

Another easier solution is to change your server IP.