I was using Microsoft Outlook 2010 since I joined my first company. It is the best in all its features. It is very easy to use and flexible. Be it, composing a mail or creating a task, or creating a meeting invite.
We can flag any task or an email. It gives reminders to all such flagged events.
We can apply rules which automatically moves the emails to specific folder based on "mails from" or "mails To", etc.