Transactional Email Sending via API and SMTP Relay

With the Highest Inbox Results


Marketers who want a quick, streamlined experience. Developers who send transactional email through their own applications.


The first transactional email service to add tracking and authentication. Send via SMTP relay servers or use our transactional email API.


Open/click tracking, and Google Analytics integration. Inbox delivery with DKIM, SPF, a tracking domain, and dedicated IP addresses.
  • Tracking

    Track opens and clicks for your messages. View SMTP logs for every message. See bounces, unsubscribes, complaints and blocks as well. 100% transparency into your sending. Send using our API or relay servers.

  • Deliverability

    Optimize delivery to the inbox using DKIM, SPF, and a custom tracking domain for better sending reputation and branding. IP addresses monitored by delivery specialists. Send using dedicated IPs.

  • Application Programming Interface

    Send emails, access reports, and manage account information with our API. Use email events to trigger a call to your web service and easily sync transactional email data with your own database using our event API/webhooks feature.

  • Live US-Based Support

    Support provided by trained email experts located in the United States. 24/7 emergency support for paying customers. Call us or submit a ticket.