3 free email and calendar apps to use instead of Outlook by Microsoft
The best free alternative to Outlook is Thunderbird. Handles multiple accounts, calendars, contacts and spam filtering, covering what most people use Outlook for.
Other great options: eM Client and Mailspring.
Quick pick: To manage several mailboxes with a calendar, use Thunderbird (open source). If you want an Outlook-like interface with Exchange support, use eM Client.
Reviewed November 2026 against each vendor's official website.
Free plans and trial lengths are set by the vendor and can change. Check the official website before signing up.
Nothing matches this filter.
Handles multiple accounts, calendars, contacts and spam filtering, covering what most people use Outlook for.
Open-source email client from Mozilla, the makers of Firefox. Handles multiple mailboxes, calendar, contacts, spam filtering and email encryption.
Platforms: Windows · Mac · Linux · Android
The closest look to Outlook, with Exchange support; free for 2 accounts.
Modern Outlook-style email client with calendar, tasks, contacts and Exchange support. The free version allows two email accounts.
Platforms: Windows · Mac
A clean, good-looking mail client with fast search.
Clean, open-source email client with fast search and a unified inbox for several accounts.
Platforms: Windows · Mac · Linux
| App | Type | Platforms | Ease of use | GitHub stars |
|---|---|---|---|---|
 Thunderbird | Open source | Windows, Mac, Linux, Android | Easy to use | — |
 eM Client | Freemium | Windows, Mac | Easy to use | — |
 Mailspring | Open source | Windows, Mac, Linux | Easy to use | 17,998 |
Open source: anyone can use, study and modify it, including businesses. Free: no cost, but the code is closed. Freemium: a lasting free plan with paid tiers for extra features. Source available: code is public but the license adds conditions.
The most popular picks are Thunderbird, eM Client and Mailspring. To manage several mailboxes with a calendar, use Thunderbird (open source). If you want an Outlook-like interface with Exchange support, use eM Client.
Yes. Use the ImportExportTools NG add-on in Thunderbird, or simply sync over IMAP: add the same email account to Thunderbird and your mail downloads automatically.
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