However, if you use both Firefox and Mozilla's e-mail client Thunderbird, Sunbird is an ideal calendar component although most would probably be better sticking to Outlook's calendar.

Due to the more limited resources of the Thunderbird community compared to Mozilla there is little chance of a Android version in near future. It also doesn't seem to be updated very often and looks like that Mozilla have put it on the back-burner for now. There is no mobile version of Thunderbird for any mobile OSs including iOS and Android. On the downside, Sunbird doesn't feature integration with either iCal or Google Calendar, which you'd expect as standard really.

You can also extend Sunbird with a series of free add-ons from the Sunbird site. Like most of Mozilla's products, it also seems very safe and allows you to set a password to access it. There's also a powerful search tool that finds events by keyword. Thunderbird is a free and open-source email, calendaring, newsfeed, and chat client with more than 20 million active monthly users across Windows, macOS, and Linux. K-9 Mail is an open-source Android email client available on the Google Play Store. Adding an event simply involves clicking on the 'Add Event' box in the top left-hand corner. K-9 Mail is joining the Mozilla Thunderbird project. It is based on the same platform that Firefox uses. The interface of Mozilla Sunbird is very simple. Thunderbird is a powerful and customizable open source email client with lots of users.

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