You simply install and emails are automatically tracked. The circle will appear when the tracking is enabled on the sent email and a checkmark will appear when it has been read. This is a simple app for tracking sent emails that will work for unlimited email accounts. Simply add your email accounts and it works. It works for all email clients. It tracks sent messages and if they are read. It doesn't track read messages, it only tracks if your messages are read.

Email Tracker works with Gmail, Outlook / Hotmail, Google Inbox, G Suite / GSuite / Google Apps, Office 365 Outlook, and Yahoo Mail. It works for all email clients and it is free to use. You will have to use the extension for Gmail, Hotmail, G Suite, and Office 365.