Parece que eles apenas rotacionaram o certificado.
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, O=Symantec Corporation, OU=Symantec Trust Network, CN=Symantec Class 3 Secure Server CA - G4
Validity
Not Before: Jun 23 00:00:00 2015 GMT
Not After : Jun 22 23:59:59 2016 GMT
Subject: C=US, ST=California, L=Sunnyvale, O=Yahoo Inc., OU=Information Technology, CN=smtp.mail.yahoo.com