Clerk Auth email verification landing in Spam — setting up custom domain signing and SPF alignment

API & SMTP Integration
1

Our Clerk Auth verification codes are getting routed to Spam in Gmail. How do we route Clerk auth emails through AutoSend custom SMTP to ensure inbox placement?

2

Diagnosing Clerk Auth Deliverability Issues

When Clerk sends emails from shared system addresses (clerk.app), receiving mail servers flag messages containing OTP codes or login links due to shared domain reputation.

Solution: Route Clerk Emails via Custom SMTP in AutoSend

  1. Obtain AutoSend Credentials:

    • SMTP Host: smtp.autosend.com
    • Port: 587
    • User: autosend
    • Password: AutoSend API Key

  2. Configure Clerk Dashboard:

    • Navigate to Clerk Dashboard → User & Authentication → Email, SMS, WhatsApp.
    • Scroll to Custom SMTP.
    • Enable Custom SMTP and enter host smtp.autosend.com, port 587, and your credentials.
    • Set the From Email to login@yourdomain.com.

  3. Verify DMARC & SPF Alignment:
    Ensure login@yourdomain.com has a SPF record containing include:autosend.email and a published DMARC record (v=DMARC1; p=none;). This guarantees strict alignment for Clerk OTP codes.