Sylpheed!

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.

Mailbird is a Windows based email client which design and style match Windows 7, 8 and XP’s native styles. Mailbird provides clean, simple and lightning fast email experience.

Opera Mail powerfully organizes, indexes, and sorts your messages.

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

Geary is a lightweight email program designed around conversations and built for the GNOME desktop.

Claws Mail is an email client (and news reader), based on GTK+, featuring

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

Newton is a subscription-based service that supercharges your email with power features across Mac, Windows, iPhone, iPad, Apple Watch, Android Phone, Tablet and Wear.Works with Gmail, Exchange, Yahoo Mail, Outlook, iCloud, Google Apps, Office 365 and IMAPSupports Calendar for Gmail, Google Apps and Exchange (EWS)All the users will be started off with a 14-day free trial, during which you can access all the features including Read Receipts, Snooze, Send Later, Undo Send, Sender Profile, Connected Apps and moreOnce the trial ends, still working for free but Subscribe for $49.99 / year if you'd like to continue using premium featuresUse your Newton account to instantly access your email anytime, across ALL your devices? Instant push notifications for ALL types of email? Calendar Support - Create events, get notified about upcoming events, RSVP invites and create events from an email? Email Tracking - WhatsApp-style Read Receipts for ALL accounts? Sender Profile - Get job title, organization info, location, LinkedIn, Facebook, Twitter profiles and more? Snooze - Deal with email only when you want to? Connected Apps - Add important emails to your favorite productivity apps like Todoist, Evernote, OneNote, Pocket, Trello, Zendesk, Salesforce and Asana? Send Later - Schedule emails to be sent at the perfect time? Undo Send? Custom Inbox Swipes - for actions like Delete, Archive, Mark as Read, Mark as Spam and more? Supports all versions of Exchange? Attach/save files from/to Google Drive, Box, Dropbox, OneDrive & more? Remote Wipe your data in case you lose your device? Switch From address - Forward or reply to emails from your preferred account? Custom Folder Sync - Get notified about emails that land in your folders? Supports 15 languagesBut wait...there’s more!- HTML signatures- Email Aliases- Turn on/off Conversations- Swipe between emails- Easy on battery and data - Passcode Lock - Mark as Spam- Interactive notifications- Unified Inbox »

Icedove is the Thunderbird email client rebranded by Debian .

Trojitá, is a fast Qt IMAP e-mail client that respects open standards and facilitates modern technologies. Trojitá values vendor-neutrality that IMAP provides and is committed to be as interoperable as possible.

Windows 10 has Mail and Calendar apps already built in.