Top 12 Open-Source Alternatives to Microsoft Outlook

Product categories

Appointments and Scheduling Calendar Calendar And Scheduling Email Email Clients Email Management Email Service Provider Encryption Enterprise Communication Hosted Email SMTP Server Self-hosted Email

Summary

The top open-source alternatives to Microsoft Outlook are Spark Mail, Tutanota, and Mailspring. One of the criteria for ordering this list is the number of mentions that products have on reliable external sources. You can suggest additional sources through the form here.

Spark Mail Landing Page
1

Spark Mail

Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues
Pricing:
- Open Source
#Email #Email Clients #Calendar 30 social mentions
Tutanota Landing Page
2

Tutanota

Get your encrypted mailbox for free.
Pricing:
- Open Source
#Email #Email Clients #Enterprise Communication 177 social mentions
Mailspring Landing Page
3

Mailspring

Mailspring is a mail client for Mac, Windows and Linux.
Pricing:
- Open Source
#Email #Email Clients #Calendar 25 social mentions
Simple Calendar Landing Page
4

Simple Calendar

A simple calendar with events (optional recurring and reminders), week numbers and a customizable...
Pricing:
- Open Source
#Calendar #Appointments and Scheduling #Email 99 social mentions
FairEmail Landing Page
5

FairEmail

Open source, privacy friendly email app
Pricing:
- Open Source
#Email #Email Clients #Calendar 52 social mentions
Roundcube Landing Page
6

Roundcube

Web-based IMAP email client
Pricing:
- Open Source
#Email #Email Clients #SMTP Server 16 social mentions
iRedMail Landing Page
7

iRedMail

A fully fledged, free email server solution, an open source project (GPL v2).
Pricing:
- Open Source
#Email #SMTP Server #Self-hosted Email 2 social mentions
Rainloop Landing Page
8

Rainloop

RainLoop is a web based email client.
Pricing:
- Open Source
#Email #Email Clients #Email Management
Mailpile Landing Page
9

Mailpile

Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.
Pricing:
- Open Source
#Email #Email Clients #Email Management
Calendar Lock PEA Landing Page
10

Calendar Lock PEA

Calendar Lock PEA is an encrypted desktop calendar with a day, week and month view. The shown calendars are never stored unencrypted on your disk, but exist only in the RAM. Platform-independent, Open Source, no installation or registration required.
Pricing:
- Open Source
#Calendar #Appointments and Scheduling #Encryption
Mail-in-a-box Landing Page
11

Mail-in-a-box

Mail-in-a-Box provides webmail and an IMAP/SMTP server for use with mobile devices and desktop mail software and also includes contacts and calendar synchronization.
Pricing:
- Open Source
#Email #Self-hosted Email #Email Service Provider 115 social mentions
mailcow Landing Page
12

mailcow

An open source mailserver suite.
Pricing:
- Open Source
#Email #Self-hosted Email #Email Service Provider 82 social mentions