This was happening a lot last year when sending email to my hotmail, yahoo friends.  It just started again a few weeks ago to Yahoo....please help. below is the reject message

This message was created automatically by mail delivery system.

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

The original message was received at Wed, 04 May 2016 08:57:02 -0700  from REMOVED FOR PRIVACY[REMOVED FOR PRIVACY]

    ----- The following addresses had fatal errors -----   

   [Status: Error, Address: <REMOVED FOR PRIVACY>, ResponseCode 421, 4.7.0 Temporarily Deferred]

Message will be retried for 4 more day(s)

    ----- Transcript of session follows -----