Hi Teefers Thunderbird for Android doesn't have a calendar feature. It's a popular request so maybe the Thunderbird team will add this in the future. Please consider up-voting the idea on Mozilla Connect. The Thunderbird team take these ideas into consideration when reviewing their priorities and road maps. https://connect.mozilla.org/t5/ideas/calendar-support-on-thunderbird-mobile/idi-p/76394 In the meantime, Google calendar or one of the alternative open source apps such as Etar should provide the functionality you need.