🔐 Double Opt-In Email Verification System with Google Sheets

Description

This template implements a professional Double Opt-In email verification system using Google Sheets as a database. The workflow collects user emails, generates unique verification codes, stores them securely, and validates user access before proceeding with your main form.

How it Works

User submits their email through an initial form
System generates a unique 6-digit verification code
Code is stored in Google Sheets along with user data
Verification email is sent to the user
User enters the code to verify their email
Upon successful verification, user accesses the main form

Setup

Follow these steps to configure the workflow:

1. Google Sheets Configuration

Create a Google Sheets spreadsheet with the following columns:

| Column Name | Data Type | Description |
|----------------|-----------|--------------------------------------|
| Start Date | String | Timestamp of form submission |
| ID | String | Workflow execution ID |
| Accepts Terms | String | Terms acceptance flag |
| Email | String | User's email address |
| Code | String | 6-digit verification code |

2. Google Sheets Connection

In n8n, go to Credentials
Add new credential for Google Sheets OAuth2
Follow the OAuth2 authorization flow
In the workflow, update the "Store Data" node:
Replace YOUR_GOOGLE_SHEET_ID with your spreadsheet ID
Select the correct sheet tab

3. SMTP Configuration

Add SMTP credentials in n8n:
Go to Credentials > Add new > SMTP
Enter your SMTP server details
Configure port, username, and password
Update the "Send Email" node:
Change sender email to your domain
Customize subject line and message body
Set reply-to address

4. Form Customization

Entry Form: Customize the title and privacy policy text
Email Form: Update the description for your use case
Verification Form: Modify instructions as needed
Main Form: Add or modify fields for your requirements

Configuration

Email Settings

From Email**: Replace [email protected] with your sender address
Subject**: Customize the verification email subject
Message**: Personalize the email template with your branding
Reply-To**: Set your support email address

Form Messages

Update all form descriptions to match your brand voice
Customize button labels
Modify error messages for better user experience

Benefits

GDPR Compliance**: Ensures legitimate user consent
Spam Reduction**: Validates email ownership
Data Quality**: Maintains clean contact lists
User Trust**: Professional verification process

Use Cases

Newsletter subscriptions
User registration flows
Marketing campaign sign-ups
Lead generation forms
Event registrations

Error Handling

The workflow includes:
Invalid code detection
Second attempt opportunity
Process restart option after multiple failures
Clear error messaging

Security Features

Unique 6-digit codes for each session
Temporary code storage
Validation against stored data
Multiple attempt limits

Tags
Double Opt-In, Email Verification, Forms, Google Sheets, GDPR, Data Protection, Email Marketing, Lead Generation

Requirements

n8n v1.0+
Google Sheets account
SMTP server access
Basic understanding of n8n workflows

Support

For questions or issues with this template:
Check the sticky notes in the workflow for detailed explanations
Review the setup instructions above
Ensure all credentials are properly configured
Test with a personal email address first

Best Practices

Test the complete flow before going live
Monitor Google Sheets for verification attempts
Set up email delivery monitoring
Consider implementing code expiration (advanced feature)
Keep form messages clear and concise