I have two mail servers (different domains) I own plus two more outside
email addresses and non of them can send to @yahoo.com addresses for
several days.  Anyone else having trouble?
 
The domains are cornerstonehome.com, harriscapitalmortgage.com,
hotmail.com, and loopadvertising.com.
 
The first two are both servers I own, different IP's same router all on
a TWTC network.  The next one is obvious... Hotmail, and the third is
operated by GoDaddy.com.  No dice with any of them.  The first two are
in good health and can send to other addresses just fine, the MTU
accepted by yahoo is the same as my default max MTU and I can trace it
down in 7 hops, so it does not seem like a connectivity issue.  I don't
get bounces, I just can't deliver.