Updated August 2019:
The information below only applies to our older Legacy Newsletter Templates. Tables are not currently available in our Third Generation Editor. They are however a feature our Product Team is collecting feedback on.
Thank you for reaching out. I see that you are currently working on an email in regards to a Christmas calendar. If you are looking to have a calendar appear in your email, one thing you can do is create a table, and put the dates and titles of different events in the cells of that table. I hope this helps.