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Microsoft Outlook, part of the Microsoft Office Suite (not to be confused with Microsoft Outlook Express), is a personal information manager that lets you manage your e-mail, calendar, contacts, and tasks.

eM Client is a full featured email client with a modern and easy to use interface. - offers calendar, tasks, contacts and even chat.- fully optimized to run smoothly on Windows XP, Vista, 7, 8 and 10.- supports all major services including Gmail, Exchange, iCloud, and Outlook.com.- easily imports your data from most of the other e-mail clients. This includes Microsoft Outlook, Outlook Express, Windows Mail, Windows Live Mail, Thunderbird, The Bat and more.- fully supports touch devices like touch-enabled laptops, tablets and hybrid devices. Use your email client easily in a modern way.- finds any email, contact or attachment in seconds with eM Client's super-fast search. »

Apple Mail changes the way you interact with your email every day.

Postbox is an email application that helps you organize your work life and get stuff done.

Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.

Org-mode is for keeping notes, maintaining ToDo lists, doing project planning, and authoring with a fast and effective plain-text system.

EssentialPIM lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.

Airmail is a lightweight and lightning fast mail client for Mac.

Sylpheed is a simple, lightweight but featureful, and easy-to-use e-mail client (mailer, MUA).

Keep track of your busy schedule and share it with others using Calendar. Create separate calendars — one for home, another for school, a third for work, and so on. See all your calendars in a single window or choose to see only the calendars you want. Calendar lets you create invitations using information from Contacts, update your guest list, keep track of responses, and receive the latest status information. When you or another Mac user receives a Calendar invitation via Mail, it’s automatically added. Calendar also works with iCloud, Yahoo!, and Google. And when you use iCloud, every Calendar edit you make on your Mac automatically appears on your iPad, iPhone, and iPod touch. So no dinner dates are missed, no meeting goes unattended, and no anniversary is forgotten. »

Rainlendar is a feature rich calendar application that is easy to use and doesn't take much space on your desktop. The application is platform independent so you can run it on all major operating systems: Windows, Linux and Mac OS X. The appearance can be customized with skins and you can even mix different skins together. It is possible to use Rainlendar with other calendar applications too. Rainlendar uses the standard iCalendar format to store its events and tasks so you can easily transfer them between applications. You can also subscribe to online calendars including the Google Calendar and edit your Outlook appointments directly in Rainlendar*. »

MyLifeOrganized (MLO) is a personal task outliner and to-do list manager which will help you to organize your goals, projects and tasks into a tree.

Fantastical is a flexible calendar with natural language event creation, a beautiful calendar and event list, support for CalDAV (including Google Calendar delegates) automatic alarms, and instant searching.