Issue: A "Mailtrack is offline" error appears after reinstalling Mailtrack on your browser.
Explanation: This is caused by the cookies that your browser has stored for Mailtrack. Deleting the cookies for Mailtrack then refreshing the browser tab containing your Gmail account will normally fix this error.
To delete the cookies for Mailtrack:
1) In a new tab in Chrome, copy/paste chrome://settings/content/all then press enter.
2) Search for mailtrack.io using the search option provided (as shown in the image below), then click on the trash can delete the cookies for Mailtrack.