🔐 Double Opt-In Email Verification with Google Sheets

This n8n workflow implements a professional double opt-in email verification system using Google Sheets as a secure database. It collects user emails from an initial form, generates a unique 6-digit verification code, stores the data (including timestamp, ID, terms acceptance, email, and code) in Sheets, and sends a verification email via SMTP. Upon code entry, it validates against Sheets and unlocks the main form upon success.

The workflow ensures high security and compliance by preventing fake sign-ups and confirming genuine interest. Key nodes include webhook for form submissions, code generation logic, Google Sheets append/read operations, and email sending. It's ideal for surveys, newsletters, lead gen forms, or any email-gated content.

Setup is straightforward: create a Sheets spreadsheet with specified columns, configure OAuth2 credentials for Sheets, add SMTP credentials, and update sheet ID in nodes. Benefits include time savings on custom coding, reduced bounce rates, GDPR-friendly opt-ins, and scalable automation for high-volume forms. Use cases span marketing (newsletters), finance (client onboarding), e-commerce (waitlists), and HR (applicant tracking).