If your email thread does not include any tracked messages, the Tracking box at the top of the thread will not be shaded in green. If you click on the Tracking box, you'll see a notice that the email thread does not include any tracking data. The "No Tracking Data" message will also be shown on inbound messages that have not been sent a tracked reply.
To ensure that future messages are tracked, visit the Yesware > Preferences drop down menu in the top left of Gmail. From there, click “Compose Options” and toggle ON “Track Opens”. In addition, the Track button at the bottom of the compose window must be checked.
Since our tracking is image-based, you will not be able to use Yesware tracking in plain-text mode. Plain-text mode strips all formatting and images, thus disabling our tracking pixel. To switch from plain text to rich text formatting in Gmail, open up a new compose window, click on the down arrow in the Compose toolbar, and uncheck "Plain Text Mode”.