Automated Email Verification & Onboarding with VerifiEmail, Gmail & Slack

Customer Onboarding Email Verification

Automated email verification and welcome email workflow that validates new user signups, prevents fake emails, and creates a seamless onboarding experience with real-time team notifications.

Features

✅ Real-time email validation with VerifiEmail API
✅ Automatic data sanitization (lowercase, trim whitespace)
✅ Smart typo detection and correction suggestions
✅ Disposable email domain blocking
✅ Professional HTML welcome emails with responsive design
✅ Automatic duplicate prevention in Google Sheets logging
✅ Real-time Slack notifications for sales/marketing teams
✅ MX record and SMTP deliverability checks

What You Need

Required Accounts/APIs:

VerifiEmail API - For email validation (verifi.email) Gmail account (or SMTP server) - For sending welcome emails Google Sheets - For logging verified users Slack workspace - For team notifications (optional but recommended)

Setup Instructions

Create Google Sheet Create new spreadsheet named "Verified Users" Add headers: Name | Email | Status | Verified At | Original Email | Validation Score

Connect Credentials Add VerifiEmail API key in n8n credentials Connect Gmail via OAuth2 (enable 2FA, generate app password if needed) Connect Google Sheets via OAuth2 Connect Slack workspace via OAuth2

Customize Email Template Open "Personalize Welcome Email" node Replace "Your Company" with your brand name (appears 3 times) Update CTA URLs: yourapp.com/dashboard → Your actual dashboard URL yourapp.com/getting-started → Your docs/guide URL yourapp.com/support → Your support page URL Modify colors: Purple gradient #667eea to #764ba2 (line 37)

Configure Slack Channel Create #new-signup channel in Slack (or use existing) Update channel in "Team Notification" node

Test Workflow Activate workflow Copy webhook URL from Webhook node Test with: curl -X POST [webhook-url] -H "Content-Type: application/json" -d '{"name":"Test User","email":"test@gmail.com"}'

Integrate with Your Signup Form Point form submission to webhook URL Ensure payload includes name and email fields

Input Format

Send POST request to webhook with this JSON:

{ "name": "John Doe", "email": "johndoe@gmail.com" }

The workflow handles various input formats (nested in body field, query params, etc.) and sanitizes automatically.

Output

After execution, you'll get:

Email validated via VerifiEmail API with deliverability score Welcome email sent to user with personalized greeting and CTAs User logged to Google Sheets with timestamp and validation details Slack notification sent to team with user details and status Invalid emails blocked with typo correction suggestions prepared

For Valid Emails (~85-90%): Professional HTML welcome email delivered Entry added to "Verified Users" sheet Real-time Slack alert to #new-signup channel

For Invalid Emails (~10-15%): Workflow stops with error message No email sent (prevents bounces) Typo suggestion prepared (e.g., gmial.com → gmail.com)

Customization

Change Email Design: Edit the "Personalize Welcome Email" node HTML: Colors**: Change gradient in line 37: background: linear-gradient(135deg, #667eea 0%, #764ba2 100%) Logo**: Add `` tag in header section Buttons**: Modify CTA text and links in lines 45-65 Footer**: Update copyright year and company name

Modify Validation Rules: In "Prepare Correction Email" node, add more typo patterns: const commonTypos = { 'gmial': 'gmail', 'gmai': 'gmail', // Add your custom patterns: 'yourdomain': 'yourcorrectdomain' }

Enable Correction Email Sending: Replace "Stop and Error" node with Gmail "Send Email" node: Connect from "Prepare Correction Email" Use {{ $json.email }} as recipient Use {{ $json.emailBody }} as message User receives helpful correction suggestion instead of silent failure

Add More Notification Channels: After "Log Valid Users" node, add: Discord webhook for team notifications Microsoft Teams connector Email to sales@ or support@ Custom webhook to your CRM

Log Invalid Attempts: Add Google Sheets node after "Prepare Correction Email": Create "Invalid Attempts" tab in same spreadsheet Log: Name, Email, Reason, Suggestion, Timestamp Analyze patterns weekly for form improvements

Troubleshooting

"undefined" error in Data Sanitization: Check webhook payload structure Verify name and email fields are present Test with the debug code provided in sticky notes

All emails marked as invalid: Verify VerifiEmail API key is active Test API directly at verifi.email dashboard

Welcome emails not sending: Confirm Gmail OAuth2 is connected (check for expired tokens) Verify sending limits not exceeded Check spam folder if testing with personal email Review Gmail "Sent" folder for delivery confirmation

No Slack notifications: Verify OAuth2 connection is active Check bot has permission to post in #new-signup channel Confirm channel ID is correct Test Slack credentials in n8n

Duplicate entries in Google Sheets: Verify "Email" is set as matching column Confirm operation is "Append or Update" not just "Append" Check Sheet1 has the exact column names expected

High validation failure rate: Review invalid emails in execution logs Check for form submission issues (bots, testing) Verify VerifiEmail API is not blocking legitimate domains

Performance Optimization

For high-volume signups (>100/day): Switch Slack notifications to hourly digest Implement rate limiting on webhook Consider caching frequent domain validations Use Google Workspace for higher email sending limits

Maintenance

Weekly: Check VerifiEmail API usage and quota Review Slack notifications for anomalies Scan Google Sheets for data quality Test with sample signup

Monthly: Archive old Google Sheets data (>90 days) Review invalid email patterns Update email template if needed Audit credential security

Support

For issues or questions, visit the n8n community forum.