Proton's human verification is a check during sign-up that you are a person, not a spam bot. It offers a CAPTCHA, a code to another e-mail address, or a code by SMS. Proton says it keeps no CAPTCHA data and stores neither your phone number nor your e-mail, only a cryptographic hash of them. If the CAPTCHA works for you, it reveals the least.
What Proton human verification is
Every Proton account comes with Proton Mail, so the check also appears when you only want Drive, Pass or VPN. Its purpose is to protect Proton's e-mail reputation: if spammers mass-produced Proton addresses, other providers would start blocking mail from Proton's servers.
Proton Mail at a glance
- Virtual numbers
- Depends on the number range
- Code sent by
- SMS
- Code length
- 6 digits
- Asks for the number again later
- No
- One number per account
- No
The options: CAPTCHA, e-mail, SMS
| What you do | What Proton keeps | |
|---|---|---|
| CAPTCHA | Solve a short puzzle | Nothing, according to Proton |
| Type a code sent to another address | A hash of the address | |
| SMS | Type a code sent to your phone | A hash of the number |
The hash lets Proton notice the same address or number being used again and again, without being able to read it.
Which options you see is up to Proton. On Tor, or when someone signs up for several accounts, it tends to drop the CAPTCHA and offer only e-mail or SMS.
Which option protects your privacy most
- CAPTCHA. Nothing is sent anywhere, and Proton says it saves no CAPTCHA data.
- E-mail code. Proton keeps only a hash, but your other mail provider sees a message from Proton arrive.
- SMS code to your own number. Proton keeps only a hash, but your carrier sees the text, and the number is tied to you by contract.
- SMS code to a temporary number. Proton keeps a hash of a number that is not yours, and nothing points back to your own line.
Code not arriving
- CAPTCHA fails Switch to the e-mail or SMS option instead of trying the puzzle again and again.
- SMS does not come Check the country code. On a temporary number, switch to another number in the app after about two minutes.
- E-mail does not come Look in the spam folder of the other address, and check that you typed it correctly.
- Nothing works, or no options appear Contact Proton support. Proton names this as the route when none of the options gets you through.
Common questions
Does Proton Mail require a phone number?
No. A phone number is one of three options for human verification. A CAPTCHA or an e-mail code also works when Proton offers them.
Does Proton store my phone number?
Proton says it does not. It keeps a cryptographic hash, which shows that a number has been used before without revealing the number.
Why does Proton only offer SMS or e-mail?
Proton is more likely to skip the CAPTCHA on Tor or when it sees several accounts being created. The e-mail option avoids a phone number entirely.
Will Proton ask for the number again later?
No. Human verification is part of sign-up. The number you use there is not your login or a recovery method unless you add it yourself.