ReturnPath company has news for you.
Please see the changes on certification standarts below;
New Certification Program Enhancements
Important Program Standards Change
Similar to email senders, mailbox providers pay close attention to mail quality and subscriber feedback. Mailbox providers occasionally tighten criteria for acceptable mail performance in an effort to provide a high quality mail experience. As you know, we have been working closely with Yahoo to gradually reduce the Yahoo complaint threshold for Certification compliance. We informed Certification members in May that the Yahoo inbox complaint rate threshold was reduced to 0.7%, and we are now taking the next step to lower the inbox complaint rate threshold to 0.6%. This change to Certification Standards for the Yahoo inbox complaint rate threshold from 0.7% to 0.6% will take effect on October 31, 2014.
You should review the data on your Return Path Certified Daily Performance Report to assess your readiness for the upcoming threshold changes. If any of your IPs are not in compliance by October 31, that IP will be suspended and will no longer receive Certification benefits at Yahoo.