Must-have Add-ons in Thunderbird

• Auto Compress File - to compress attachments into a single zip file with 1 click
  
• Folder Pane View Switcher - to switch the view in folder pane
  
• gContactSync - to synchronize Contacts with Google Contacts so that all your Android devices contacts are synced as well
• Lightning - to add calendar and task funtionality as in Outlook
• LookOut - to support calendar event and invitation (TNEF encoded) from Outlook
• More Snooze - customize the snooze duration options for calendar event and task reminders
• Provider for Google Calendar - to sync calendar with Google Calendar so that all your Android devices calendars are synced as well
• QuickFolders - easily access to frequently used folders
• Tag Toolbar - easily tag emails