Transactional Email Best Practices

Transactional vs Marketing Email

Transactional emails are triggered by a user action and contain information the user expects to receive: password resets, order confirmations, shipping notifications, account alerts. Marketing emails are sent to promote products or content. The distinction matters legally (transactional emails are exempt from some CAN-SPAM requirements) and technically (they should use separate sending infrastructure).

Why separate infrastructure matters:

• Marketing emails get more spam complaints, which can affect your sending reputation
• Transactional emails are time-sensitive — a password reset delayed by marketing throttling is a poor experience
• Separate streams let you monitor deliverability independently
• Many ESPs offer different pricing for transactional vs marketing volume

Design Principles

Transactional emails should prioritize clarity and speed over branding:

• Get to the point immediately — the critical information (confirmation code, tracking link, receipt total) should be visible without scrolling
• Minimal design — simple layout, limited images, fast loading
• Clear hierarchy — use headings and whitespace to separate information blocks
• Functional CTA — one primary action button (track package, reset password, view receipt)
• Plain text alternative — always include a well-formatted plain text version

Avoid the temptation to load transactional emails with marketing content. A small "you might also like" section is acceptable; a full product catalog is not. Users came for specific information — respect that intent.

Delivery Requirements

Transactional emails have stricter delivery requirements than marketing emails:

• Speed — password resets and verification codes should arrive within seconds, not minutes
• Reliability — 99.9%+ delivery rate is the minimum acceptable standard
• Retry logic — implement automatic retries with exponential backoff for failed deliveries
• Fallback channels — consider SMS fallback for critical transactional messages

ESPs specializing in transactional email (Postmark, Brew, Amazon SES) consistently outperform all-in-one platforms for delivery speed and reliability. If transactional email is critical to your user experience, invest in dedicated infrastructure.

Monitoring Transactional Email

Monitor these metrics for transactional email health:

• Delivery latency — p50 and p99 delivery times. Alert if p99 exceeds 30 seconds.
• Bounce rate — should be under 2%. Investigate sudden spikes immediately.
• Open rate — transactional emails typically see 60-80% open rates. A drop signals deliverability issues.
• Complaint rate — should be near zero. Any complaints on transactional email indicate a problem.

Set up automated alerting for anomalies. A transactional email failure at 2 AM should wake someone up — users cannot reset their passwords or confirm their orders until it is fixed.