Yahoo will be dropping its Mail Classic interface on 3 June. Despite releasing an interface update of its email service last year, Yahoo has allowed users to continue using the old version. Once users have upgraded to the new interface, they will be presented with a new terms of service which includes "automated content scanning and analyzing of your communications content". Yahoo has stated that all information collected is for the purpose of delivering product features, relevant advertising, and abuse protection.
For those who aren't willing to share their data, Yahoo has offered two options: users can either download their Yahoo! Mail to another IMAP client or close their account.
Source: Yahoo Help