Email Verification

When require_email_verification is enabled, users must verify their email address before they can complete the OAuth2 login flow. Unverified users are shown a verification page after login instead of receiving an authorization code.

Verification flow

sequenceDiagram
    actor User
    participant Browser
    participant IdP as Autentico
    participant Email as SMTP Server

    User->>Browser: Sign up or log in
    Browser->>IdP: POST /oauth2/login
    IdP->>IdP: Credentials valid, email not verified
    IdP->>Browser: Render verify_email page (mode: blocked)
    IdP->>Email: Send verification link
    Email->>User: Email with verification URL
    User->>Browser: Click verification link
    Browser->>IdP: GET /oauth2/verify-email?token=...
    IdP->>IdP: Validate token, mark email verified
    IdP->>Browser: 302 -> redirect_uri?code=AUTH_CODE

The verification link contains a cryptographically random token (32 bytes, base64url-encoded). Only the SHA-256 hash of the token is stored in the database, so a database compromise does not expose valid verification links.

Configuration

Enable email verification and set the token expiration via the admin API:

curl -X PUT https://auth.example.com/admin/api/settings \
  -H "Authorization: Bearer $ADMIN_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "require_email_verification": "true",
    "email_verification_expiration": "24h"
  }'

Settings

Setting	Default	Description
require_email_verification	false	When true, unverified users cannot complete login
email_verification_expiration	24h	How long a verification link remains valid

SMTP requirements

Email verification requires a working SMTP configuration. Set these settings via the admin API or Admin UI:

Setting	Description
smtp_host	SMTP server hostname
smtp_port	SMTP server port (typically 587)
smtp_username	SMTP authentication username
smtp_password	SMTP authentication password
smtp_from	Sender email address

Caution

Without SMTP configured, verification emails cannot be sent. Users will be stuck on the verification page with no way to receive their link.

Endpoints

Verify email

GET {oauth_path}/verify-email?token=...&client_id=...&redirect_uri=...&scope=...&state=...

Validates the verification token and, if valid, marks the user’s email as verified, creates an IdP session, issues an authorization code, and redirects to the client. The OAuth2 parameters are carried through the verification link so the login flow resumes seamlessly.

If the token is expired or invalid, the user is shown the verification page in “expired” mode with an option to request a new link.

Resend verification

POST {oauth_path}/resend-verification

Generates a new verification token and sends a fresh verification email. Accepts form-encoded parameters:

Parameter	Description
username	The user’s username
redirect_uri	OAuth2 redirect URI (carried through)
state	OAuth2 state parameter (carried through)
client_id	OAuth2 client ID (carried through)
scope	OAuth2 scope (carried through)

The endpoint always shows a success message regardless of whether the user exists, to prevent user enumeration. A random delay is added for the same reason.

Security considerations

• Token hashing – only the SHA-256 hash of the token is stored; the raw token exists only in the email link
• Single-use – once verified, the token cannot be reused
• Expiration – tokens expire after the configured duration (default: 24 hours)
• Parameter integrity – OAuth2 parameters in the verification link are protected by an HMAC signature (authorize_sig) to prevent tampering
• Timing-safe – the resend endpoint uses random delays to prevent timing-based user enumeration