FlowCrypt is a tool that allows users to send and compose emails within Gmail with PGP end-to-end encrytion, by adding a Secure Compose button that lets you send encrypted email and attachments from the Gmail web app. Users can save encrypted drafts, generate a new Public Key for encrypting or decrypting messages, and even create password-encrypted emails for users who do not have FlowCrypt installed. Just click on in, write your message, and send it. The message will get encrypted inside of your browser, on your own computer.
FlowCrypt has both free and commercial licensing. It’s free up to limited features, however, you would have to pay to access advanced features.
CHECKER PLUS FOR GMAIL
Checker Plus for Gmail is a free Google Chrome browser extension that helps you manage quickly your emails without opening Gmail directly. It keeps your Gmail messages within easy reach, with your inbox and newly received messages just a click away and also offers voice notifications. You can view your messages without having to leave your current page to launch a Gmail tab, and you can mark a message as read, delete it, or send it to the archive. It also gives the user an option to monitor any Gmail or custom labels and you can still get email alerts or notifications in the background even when the Google Chrome is closed
Although it’s Open Source, it states on its page that Extra features are available upon contributing “any” amount.
MailTag is an email tool that helps you make more sales, in less time which provides a series of free, helpful modifications to the Gmail web experience. It allows users to track emails in Gmail with real time alerts, schedule emails at your own pace of time(type now and send later) and also lets you automate follow-ups in Gmail. MailTag is ad-supported, and comes with a watermark. A premium tier removes ads and watermarks, while also providing expanded “ping sequences” that allow you to automate the email follow-up process
It offers free and unlimited real-time email tracking, email scheduling and automated email follow-up. They also offer business plans and upgrades at various pricing options.