Transactional Email Delivery Service

Postmark is a transactional email delivery service operated since 2010, now part of ActiveCampaign, that specializes in fast inbox delivery for application-generated emails including password resets, welcome messages, receipts, notifications, and alerts. The platform separates transactional and broadcast message streams onto parallel sending infrastructure, ensuring that promotional emails never degrade the deliverability or speed of critical transactional messages. Deliverability is maintained through a rigorous sender vetting process, shared IP reputation pooling across carefully screened customers, and an absolute prohibition on spam traffic, eliminating the need for dedicated IP purchases on standard plans. The REST API accepts JSON payloads with fields for sender, recipient, subject, HTML body, text body, tags, metadata, and message stream selection, with official client libraries for Node.js, Python, Ruby, PHP, and C-sharp plus SMTP relay support for any language. Email analytics dashboards display delivery rates, open rates, click-through rates, bounce rates, spam complaint rates, and delivery latency per mailbox provider including Gmail, Outlook, Yahoo, and Apple, with email logs retained for 45 days. Inbound email processing receives messages via webhook for support ticket creation, reply-by-email workflows, and email-to-task automation. The Rebound product automatically retries bounced emails on a schedule based on bounce classification and mailbox provider best practices. Postmark Skills integrate with AI coding agents like Claude Code and Cursor, enabling agent-initiated email sending without manual API key configuration. Customers include 1Password, Webflow, Betterment, Minecraft, Faire, Paddle, Indie Hackers, and Wistia, with a 95 percent customer happiness rating measured over 60-day windows.