Sunbird Alternatives for Mac OS X

Microsoft Outlook is a comprehensive personal information manager designed for managing email, contacts, calendars, and tasks.

Lightning is a comprehensive calendar and task management add-on for Mozilla Thunderbird and Seamonkey, designed to integrate seamlessly with email. It offers robust features for scheduling, task tracking, and synchronization with various online calendar services, enhancing productivity directly within your email client.

Apple Calendar is a personal calendar application developed by Apple Inc., designed to seamlessly integrate with your Apple ecosystem whether you are on macOS or iOS. It allows you to manage your schedule, appointments, and events efficiently, synchronizing across all your devices.

Rainlendar is a highly customizable calendar application for Windows, macOS, and Linux. It seamlessly integrates with popular online calendars like Google Calendar and Fantastical, offering comprehensive event and task management directly on your desktop.

BusyCal is a powerful desktop calendar application for Mac, designed to enhance productivity and organization. It offers a robust set of features for managing events, tasks, and reminders, with seamless integration across various calendar services like iCloud, Google Calendar, and Exchange.