The Calendar feature's main purpose is to help you determine the most ideal time for you to send-out your email campaigns. 

Here we store all the emails sent out by your followed companies in a calendar based overview. You are able to see what emails you received in the past and exactly what time they were sent in a send-out analysis.

Another great aspect of the Calendar is that you get to see what emails are expected for each day of the month. This includes the name of the company sending the email as well as the expected send-out time based on the usual send-out times for that specific company. So now you know what to expect on each day of the month and therefore you can better plan your own email campaigns.