European & open-source alternatives to Outlook
16 European and open-source alternatives to Outlook — privacy-friendly tools built and hosted in Europe.
Updated 9 Sep 2026 · refreshed weekly
Calenso
Swiss enterprise appointment-scheduling platform from Bern with resource management, multi-location support and video…
eM Client
A full-featured email client for Windows and Mac that synchronizes with various email services, offering email, calendar…
Kolab Now
A web-based email and groupware service that provides secure and private email accounts, calendars, address books, video…
KDE Kontact
A personal information management suite that unifies applications for email, address books, calendars, and tasks into a single…
Mailbox.org
This service provides a secure and GDPR-compliant digital workspace, offering email, cloud storage, office applications, and…
Mailfence
A secure and private email service offering encrypted email, calendars, documents, and collaboration tools, emphasizing user…
MailProfessionale
This service provides professional email hosting, allowing businesses to use their own domain for email communications, and…
Meetergo
German meeting scheduling platform from Cologne pairing Calendly-style booking with CRM integration and lead qualification…
Open-Xchange
This platform provides email, calendar, and collaboration tools, offering a familiar experience for daily work across various…
Posteo
A paid email service provider that offers secure, ad-free email accounts, calendars, and other features, emphasizing…
Proton Mail
It provides a secure and encrypted email service, offering privacy by default and protecting user data under strong Swiss privacy…
Soverin
Soverin provides private email services with a focus on security, privacy, and custom domains, offering ample storage and…
StartMail
A secure and encrypted email service that allows users to create disposable email addresses to protect their inboxes from spam…
Tuta
An end-to-end encrypted email, calendar, and contacts service that stores all user data encrypted on its own servers.
Tutanota
An end-to-end encrypted email and calendar app that automatically encrypts all user data with post-quantum cryptography, making…
Zeeg
German privacy-first scheduling platform from Berlin and a Calendly alternative, with booking pages, round-robin scheduling and…