After June 16, 2016, if users attempt to connect to Gmail from mail clients using SSLv3 or RC4, they may see connection errors for short periods of time. The change will be rolled out as a gradual change, where it may take longer than 30 days for users to be fully restricted from connecting to Gmail. The vast majority of mail clients already favor modern TLS connections over outdated ones, so the majority of users are not affected by this change. We recommend proactively updating to the recommended standards for TLS clients as a best practice.”]
Source: https://workspaceupdates.googleblog.com/2016/06/gradually-disabling-support-for-sslv3.html