#YahooMailFail enters day 5; company recommends using mobile app A message from Yahoo to Yahoo Mail users who experienced outages. Twitter / December 13, 2013 December 13, 2013, 10:52 a.m. Yahoo's email service outage, or what has come to be known on Twitter as #YahooMailFail, is entering its fifth day and continues to keep some users from accessing their messages.