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Educational and ethical use only. Only test systems you own or are explicitly authorized to test. Full disclaimer.

ProtonMail Domains (M)

Queries ProtonMail's HKP key server with a full email address to check for a PGP public key. Useful for identifying ProtonMail users on custom…

username
Official docs ↗

Platforms: Web · Last verified September 7, 2026

Queries ProtonMail’s HKP key server with a full email address to check for a PGP public key. Useful for identifying ProtonMail users on custom domains.

Only use this tool against systems you own or are explicitly authorized to test — see the disclaimer.

Getting started

Best for: Checking if an email address on a custom domain is hosted on ProtonMail. See the official site linked above for details.