Gmail is required to use the HTTPS protocol
According to CNET , HTTPS protocol has been applied by Google by default when accessing Gmail since 2010. However, Gmail is now also encoded with the ability to send / receive email under HTTPS protocol.
Google said that adopting the HTTPS protocol may slow down the process of receiving / sending emails, but every user's personal documents are enhanced with security.
It is known that HTTPS ( Secure HTTP ), a combination of HTTP protocol and SSL or TLS security protocol, allows to exchange information securely on the Internet.
HTTPS connections are often used for payment transactions on the World Wide Web and for sensitive transactions in banking information systems.