--- name: postmark-email-best-practices description: Use when asking about email deliverability, compliance (CAN-SPAM, GDPR, CASL), transactional email design patterns, list management, testing safely, or general email best practices — provider-agnostic knowledge with Postmark-specific guidance. license: MIT metadata: author: postmark version: "1.0.0" --- # Email Best Practices Postmark has delivered billions of transactional emails over 15+ years. This skill distills that expertise into actionable guidelines for building reliable, compliant, high-deliverability email systems. ## Quick Reference | Topic | Use When | |-------|----------| | **Deliverability** | Setting up SPF/DKIM/DMARC, warming a new domain, diagnosing delivery issues | | **Compliance** | Building unsubscribe flows, handling GDPR/CAN-SPAM/CASL requirements | | **Transactional Design** | Designing welcome emails, password resets, receipts, alerts | | **List Management** | Handling bounces, suppressions, list hygiene | | **Testing** | Testing safely without hurting sender reputation | | **Sending Reliability** | Idempotency, retry logic, rate limits | ## Deliverability Fundamentals The three authentication records every sending domain must have: | Record | Purpose | Priority | |--------|---------|----------| | **SPF** | Authorizes servers to send as your domain | Required | | **DKIM** | Cryptographically signs emails to prove authenticity | Required | | **DMARC** | Policy for handling SPF/DKIM failures | Required | With Postmark, DKIM is configured automatically when you verify a sender domain. SPF and DMARC must be set up in your DNS. See [references/deliverability.md](references/deliverability.md) for DNS setup, reputation factors, and domain warm-up guidance. ## Transactional vs. Broadcast Email **Never mix transactional and broadcast email in the same sending stream.** They have different delivery characteristics, compliance requirements, and reputation profiles. | Type | Examples | Compliance | Unsubscribe Required | |------|----------|------------|---------------------| | **Transactional** | Password resets, receipts, alerts, notifications | CAN-SPAM exemption possible | No (but good practice) | | **Broadcast** | Newsletters, promotions, announcements | CAN-SPAM, GDPR, CASL apply | Yes — legally required | Postmark enforces this separation with **Message Streams** — use `outbound` for transactional, `broadcast` for marketing. See [references/compliance.md](references/compliance.md) for CAN-SPAM, GDPR, and CASL requirements. ## Transactional Email Design Good transactional emails are: - **Expected** — The recipient triggered this email - **Timely** — Sent immediately after the triggering event - **Actionable** — One clear call to action - **Plain** — Minimal design; content over decoration Common transactional email types and their essential elements: | Email Type | Must Include | Avoid | |-----------|--------------|-------| | Welcome | Product name, next step CTA, support contact | Marketing upsell on day 1 | | Password reset | Expiry time, ignore-if-not-you notice, support link | Long copy | | Receipt / Invoice | Line items, total, billing address, support | Promotional content | | Shipping notification | Tracking link, estimated delivery, items | Unrelated promotions | | Security alert | What happened, when, action required, how to secure | Panic-inducing language | See [references/transactional-design.md](references/transactional-design.md) for design patterns, copy guidelines, and HTML email best practices. ## List Health Sending to invalid, inactive, or unengaged addresses is the leading cause of deliverability problems. **Key rules:** - Remove **hard bounces** immediately and permanently - Suppress **spam complaints** immediately — never re-add - Re-permission lists older than 12–18 months before mailing - Never purchase or rent email lists - Validate addresses at the point of collection See [references/list-management.md](references/list-management.md) for suppression strategies, list hygiene schedules, and re-engagement workflows. ## Testing Safely **Never test with real addresses at consumer providers** (gmail.com, yahoo.com, etc.) — it damages sender reputation. | Method | How | Use For | |--------|-----|---------| | API test token | Use `POSTMARK_API_TEST` as your server token | Validating API calls in CI/development | | Black hole | Send to `test@blackhole.postmarkapp.com` | Functional testing — appears in activity | | Sandbox server | Create a dedicated sandbox server in dashboard | Full send pipeline without delivery | | Bounce testing | `hardbounce@bounce-testing.postmarkapp.com` | Testing bounce webhook handlers | See [references/testing.md](references/testing.md) for full testing setup and domain warm-up schedules. ## Sending Reliability Production email systems need idempotency keys, retry logic, and rate limit handling to avoid duplicate sends and silent failures. See [references/sending-reliability.md](references/sending-reliability.md) for idempotency patterns, retry strategies, and rate limit handling. ## Notes - Postmark is purpose-built for transactional email — use it for triggered 1:1 emails, not bulk marketing - Deliverability is not just about authentication — it's about sending wanted email to engaged recipients - A single spam complaint from a real user is more damaging than 1,000 hard bounces - Monitor your bounce rate (keep below 2%) and spam complaint rate (keep below 0.04%) --- Source attribution: ActiveCampaign Original project: https://github.com/ActiveCampaign/postmark-skills/blob/269553ee297376a3011694caec88f0f3c6bce4aa/postmark-email-best-practices/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Dave AI. ## Upstream license notice MIT License Copyright (c) 2025 ActiveCampaign, LLC Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. # Dave AI resource metadata Creator / publisher: ActiveCampaign Original project: https://github.com/ActiveCampaign/postmark-skills/blob/269553ee297376a3011694caec88f0f3c6bce4aa/postmark-email-best-practices/SKILL.md Attribution basis: Source repository record Fields of work: Marketing Roles: Email Marketer, Growth Marketer, Marketing Analyst Specialties: Specialty not specified Tools: Tool not specified Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 7f0070352e6ecdb21ca59b4b08ea02c68c9b17d410e99fe5284f1ea2466bf352