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SMTP submission is in active development, on track for mid-October. Will run on port 587 with host/user/product-token auth, through the same suppression, webhook, and event pipeline as the existing API.

Email Gateway can send email over SMTP as an alternative to the REST API. This is useful if you're migrating from an existing SMTP setup or working with a tool or library that only speaks SMTP.

Getting your credentials

Your SMTP credentials are available in the Email Gateway App, under Settings > SMTP:

• Host: mx.email.cm.com
• Port: 587
• User: cm_smtp_gateway
• Password: Your Product Token

Port 587 is currently the only port we support, using STARTTLS: the connection starts in plaintext and upgrades to TLS before any credentials or message content are sent.

Verified domains still apply

Sending over SMTP doesn't change your domain requirements. The sending domain on each message still needs to be verified under Domains, exactly as it does when sending through the REST API.