Top 4 Open-Source Alternatives to K9

Product categories

Anti-Spam Calendar Cyber Security Email Email Clients Email Security Enterprise Communication Hosted Email

Summary

The top open-source alternatives to K9 are Spark Mail, FairEmail, and Tutanota. 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
FairEmail Landing Page
2

FairEmail

Open source, privacy friendly email app
Pricing:
- Open Source
#Email #Email Clients #Calendar 52 social mentions
Tutanota Landing Page
3

Tutanota

Get your encrypted mailbox for free.
Pricing:
- Open Source
#Email #Email Clients #Enterprise Communication 177 social mentions
SpamAssassin Landing Page
4

SpamAssassin

Use this program to "Unspam" your mailbox(es).
Pricing:
- Open Source
#Email Security #Email #Cyber Security 4 social mentions