MailTrack is an application that allows Gmail users to identify new messages and those which have already been opened. This is often beneficial for those who receive a substantial number of mails on a daily basis (such as managers of an organisation). Email tracking reports, daily reminders and line tracking are a few features associated with the basic (free) version. Upgrading to the professional variant will provide even more possibilities. The entire size of the app is only 1.2 megabytes.