Startmail vs Proton Mail Comparison (2025)

What are the differences between Startmail and Proton Mail?

Written by

Forward Email Team

Published

7/1/25

Time to read

Less than 5 minutes

We recommend Forward Email as the best alternative to Startmail.

Email Service Comparison

20 facts in comparison

Startmail	vs.	Proton Mail
Startmail "Private email you can trust" Website	vs.	Proton Mail "Secure email that protects your privacy" Website
$7/mo	Pricing	$3.99/mo
20 GB	Storage	15 GB
25 MB	Attachments	25 MB
No	Open-Source	❌ Proton Mail claims to be open-source, but their back-end actually is closed source
❌ Startmail claims to use a User Vault, but this statement has not been audited and their source code is closed-source	Sandboxed Encryption	No
No	Unlimited Domains	No
No	Unlimited Aliases	No
No	TTI	No
Yes	SMTP	❌ Requires you to download Proton Mail Bridge and forces vendor lock-in
Yes	IMAP	❌ Requires you to download Proton Mail Bridge and forces vendor lock-in
Yes	POP3	❌ Proton Mail does not support POP3
No	API	No
⚠️ Supported if both sender and recipient are using OpenPGP	E2EE	⚠️ Proton Mail rewrites your emails
⚠️ Supports OpenPGP, but does not support WKD	OpenPGP	Yes
No	WKD	Yes

Email Service Screenshots

Closed-source

Startmail

Startmail is a closed-source email service. Their website says: Private email you can trust

Startmail is a closed-source email service.

Photograph by Forward Email

Closed-source

Proton Mail

Proton Mail is a closed-source email service. Its description from its website is: Secure email that protects your privacy

Proton Mail is a closed-source email service.

Screenshot by Forward Email

Compare Startmail with 78 email services