From 21st March 2014, all European Yahoo! properties, including Yahoo! UK, will be managed from one centralised HQ in Ireland to be known as Yahoo! EMEA.
This change will affect all services offered by Yahoo! UK and other European Yahoo! services, including Yahoo! Mail.
In light of this change, Yahoo! are requiring all users of their European services to agree to their updated Terms of Service. If these Terms of Service changes are not agreed upon by users after the 21st March 2014, their accounts will be closed.
If you have a large amount of European Yahoo! users in your email lists, this change may impact your deliverability after the 21st March 2014, resulting in higher bounce rates as accounts are shut down due to non-compliance with the new Terms of Service.
For more information, see Yahoo! UK’s website.