Yahoo Mail uses the encryption technology that Gmail has applied for four years

In January, Yahoo started using the (default) HTTPS protocol for its Mail service, four years behind Gmail.
In the past few years, Yahoo has continued to implement many updates to its Mail service, including the recent upgrades to the interface with 1 TB of storage. Today, they announced a new feature for their service: From 8/1 next year, Yahoo's mail will begin to apply encryption technology to help protect the user's mail better. Specifically, from time to time, Yahoo Mail, by default, will apply encryption technology SSL (Secure Sockets Layer) or HTTPS. This is a highly secure encryption technology that helps the user's mail avoid the risk of being stolen. Yahoo has also applied HTTPS to its service earlier this year, but this is only an option, not the default protocol.
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While Yahoo's move is welcome, it may be seen as a slow response. Yahoo Mail's Gmail rival, Gmail, has applied this HTTPS protocol since 2008, and the technology has been defaulted on Gmail since January 2010; Security experts have repeatedly recommended that the http protocol is not secure enough.
Also noteworthy is that Yahoo's announcement comes just after the Washington Post reported that the US National Security Agency had deliberately collected millions of user listings; Of these, the directories collected by Yahoo Mail are more than double the total number of contacts collected from other major services combined. While the article does not state the reasons for this difference, one of the reasons may be that Yahoo has not adopted encryption technologies to protect users' email.