Heimdal vs Proton Mail Comparison (2026)

Compare Heimdal vs Proton Mail email services. In-depth analysis of features, pricing, security, privacy, and storage to find the best email provider for your needs.

Written by

Forward Email Team

Published

4/1/26

Time to read

Less than 5 minutes

We recommend Forward Email as the best alternative to Heimdal. We also support webmail: https://mail.forwardemail.net

Email Service Comparison

20 facts in comparison

Heimdal	vs.	Proton Mail
Heimdal "One Platform. Total Security." Website	vs.	Proton Mail "Secure email that protects your privacy" Website
Requires you to talk to a sales team	Pricing	$3.99/mo
Requires 3rd party	Storage	15 GB
Unknown	Attachments	25 MB
No	Open-Source	❌ Proton Mail claims to be open-source, but their back-end actually is closed source
No	Sandboxed Encryption	No
No	Unlimited Domains	No
No	Unlimited Aliases	No
No	TTI	No
❌ Requires 3rd party	SMTP	❌ Requires you to download Proton Mail Bridge and forces vendor lock-in
❌ Requires 3rd party	IMAP	❌ Requires you to download Proton Mail Bridge and forces vendor lock-in
❌ Requires 3rd party	POP3	❌ Proton Mail does not support POP3
Yes	API	No
No	E2EE	⚠️ Proton Mail rewrites your emails
No	OpenPGP	Yes
No	WKD	Yes