Cisco Secure Email Defense vs Proton Mail Comparison (2026)

Compare Cisco Secure Email Defense 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 Cisco Secure Email Defense. We also support webmail: https://mail.forwardemail.net

Email Service Comparison

20 facts in comparison

Cisco Secure Email Defense	vs.	Proton Mail
Cisco Secure Email Defense "Advanced protection to safeguard your inboxes" Website	vs.	Proton Mail "Secure email that protects your privacy" Website
Requires you to talk to a sales team	Pricing	$3.99/mo
Unknown	Storage	15 GB
100 MB	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