Blocked Emails Gmail Jun 2026

Gmail runs emails through ~20 classifiers in sequence:

swaks --to test@gmail.com --from sender@example.com --server smtp.gmail.com:587 -tls blocked emails gmail

Since 2024, Gmail has tightened requirements for senders. If your domain is not authenticated with SPF, DKIM, and DMARC , Gmail may reject your emails outright. Gmail runs emails through ~20 classifiers in sequence: