Proton Mail vs Altospam Comparison (2025)

What are the differences between Proton Mail and Altospam?

Forward Email Team
Written by
Forward Email TeamVerified
Published
7/1/25
Time to read
Less than 5 minutes
We recommend Forward Email as the best alternative to Proton Mail.

Email Service Comparison

20 facts in comparison
Proton Mailvs.Altospam

Proton Mail

Secure email that protects your privacy
"Secure email that protects your privacy"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
vs.

Altospam

Antispam, Antivirus & Anti-Phishing Software
"Antispam, Antivirus & Anti-Phishing Software"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
$3.99/moPricingRequires you to talk to a sales team
15 GBStorageRequires 3rd party
25 MBAttachmentsUnknown
❌ Proton Mail claims to be open-source, but their back-end actually is closed sourceOpen-SourceNo
NoSandboxed Encryption No
NoUnlimited DomainsNo
NoUnlimited AliasesNo
NoTTI No
❌ Requires you to download Proton Mail Bridge and forces vendor lock-inSMTP❌ Requires 3rd party
❌ Requires you to download Proton Mail Bridge and forces vendor lock-inIMAP❌ Requires 3rd party
❌ Proton Mail does not support POP3POP3❌ Requires 3rd party
NoAPIYes
⚠️ Proton Mail rewrites your emailsE2EE No
YesOpenPGP No
YesWKD No

Email Service Screenshots

Closed-source

Proton Mail

Proton Mail is a closed-source email service. Their official description reads: Secure email that protects your privacy

Proton Mail is a closed-source email service.
Screenshot by Forward Email
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Closed-source

Altospam

Altospam is a closed-source email service. Their website says: Antispam, Antivirus & Anti-Phishing Software

Altospam is a closed-source email service.
Photo by Forward Email
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Compare Proton Mail with 78 email services