Free, open-source alternatives to Microsoft Outlook

Microsoft Outlook brings email from several accounts together with calendars and contacts in one app, and it is built around Microsoft's own Outlook.com, Exchange and Microsoft 365 accounts. The open-source mail clients below do the same core job on the Mac: they connect to the mail accounts you already have and give you one place to read, sort, search and send messages.

Thunderbird is the most complete counterpart, with mail, a calendar and an address book in one program, plus filters and add-ons. Betterbird is built on Thunderbird and layers its own fixes and usability changes on top. Mailspring concentrates on mail alone, with a unified inbox, snoozing, send later and templates. Support for work accounts on Exchange differs between the three, so check how your organisation's mail server is set up before moving over.