The error message in your image indicates that your email has been flagged as spam by Gmail spam detection system. This is a 550-5.7.1 error, which is a response from Gmail servers stating that your email does not meet their standards for authentication or content.

Authenticate Your Emails

1

Add SPF Record

  • Ensure the SPF record specifies which servers can send emails on behalf of your domain.
  • Example SPF record:
    • v=spf1 include:_spf.google.com -all
2

Add DKIM Record

  • Generate a DKIM key on your mail server.
  • Add the public key as a TXT record in your DNS:
    • default._domainkey.yourdomain.com TXT "v=DKIM1; k=rsa; p=PUBLIC_KEY"
3

Add DMARC Record

  • DMARC enforces SPF and DKIM policies:
    • _dmarc.yourdomain.com TXT "v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com"

Check Your IP Reputation

  • Gmail may block emails from IPs with a poor reputation or those listed in blacklists.
  • Use tools like:
  • If your IP is blacklisted:
    • Request delisting from the blacklist provider.
    • Avoid sending bulk emails from the same IP.

Avoid Spam-Like Content

  • Write professional and clear subject lines.
  • Avoid all caps, excessive punctuation, and spammy words like "Free" or "Congratulations."
  • Ensure your email includes:
    • A valid From address.
    • A clear unsubscribe link if it is a marketing email.

Send Gradually

  • Gmail might flag a large volume of emails sent within a short period.
  • Start with smaller batches to build a good sender reputation.

Check Reverse DNS (PTR Record)

  • Ensure your mail server has a reverse DNS entry (PTR record) that matches your domain.

Test Email Deliverability

  • Use tools like Mail-Tester to analyze your email spam score.
  • Verify SPF, DKIM, and DMARC configurations.

Gmail-Specific Guidelines

Example DNS Records for Proper Email Configuration

Type Name Value
TXT @ v=spf1 include:_spf.google.com -all
TXT _dmarc v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com
TXT default._domainkey v=DKIM1; k=rsa; p=YOUR_DKIM_PUBLIC_KEY

Next Steps

  1. Implement and verify SPF, DKIM, and DMARC records.
  2. Check your server IP reputation and request delisting if needed.
  3. Monitor your email deliverability through tools like Google Postmaster Tools.