If the email is from ZeroTwo and asks you to follow a link to sign in, it is a sign-in link. ZeroTwo sends one whenever someone enters an email address on the sign-in page and selects Continue, and opening the link signs in to the account for that address. If you did not ask for it, you can ignore it.
Why it arrived
ZeroTwo emails the link to whatever address is typed in, so you can receive one without ever opening ZeroTwo yourself. The email does nothing on its own: you are only signed in if the link in it is opened. The screen shown to the person who asked for it says "Click the link in your email to sign in. The link will expire in 1 hour."
If you did not open it
- Leave the link alone and do not forward the email. Opening the link signs in to the account for your address.
- An expired or invalid link sends whoever opens it back to the sign-in page with the message "Your magic link has expired or is invalid. Please request a new one."
- ZeroTwo's sign-in page tells new users that an account is created automatically when they click the link.
If you opened it
- Add a second step. On the web or in the desktop app, open Settings > Security and switch on Two-factor authentication. After that, signing in with a link also asks for a six-digit code from your authenticator app, so the link alone is not enough.
- Sign out other devices. In the same tab, use Log out of all devices. It ends every session, including the one you are using, and other devices can take up to 30 minutes to be signed out.
- Remove the account if you do not want it. In Settings > Data Controls, find Delete account, select its Delete account button and confirm. If you cannot sign in, the Delete your account page on zerotwo.ai takes your email address and an optional note, and says ZeroTwo will confirm by email.
If they keep coming
ZeroTwo limits how many sign-in links it will send to one address in an hour and in a day. If unrequested emails keep arriving anyway, write to reed@zerotwo.ai, the address ZeroTwo's Privacy Policy gives for privacy requests, and include the dates you received them.