Email Best Practices

From the author

Use when building email features, emails going to spam, high bounce rates, setting up SPF/DKIM/DMARC authentication, implementing email capture, ensuring compliance (CAN-SPAM, GDPR, CASL), handling webhooks, retry logic, making emails accessible (alt text, headings, contrast, screen readers), or deciding transactional vs marketing.

— the description by Resend

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a structured framework for managing the entire lifecycle of email communications. It covers technical infrastructure like SPF/DKIM/DMARC authentication, legal compliance across major jurisdictions (GDPR, CAN-SPAM, CASL), and accessibility standards for screen readers and diverse email clients. It also offers guidance on transactional versus marketing email strategies, list management, and building reliable delivery pipelines with retry logic and webhooks.

What it does

Provides technical guidance for email authentication (SPF, DKIM, DMARC) to improve deliverability.
Outlines legal requirements for global email compliance including GDPR, CAN-SPAM, and CASL.
Defines accessibility standards for email content, including screen reader support and contrast.
Offers architectural patterns for transactional and marketing email workflows.
Details best practices for list management, bounce handling, and suppression lists.
Explains how to implement reliable sending with idempotency, retries, and webhook event tracking.

When to use it

When setting up a new email infrastructure for an application.
When troubleshooting high bounce rates or emails landing in spam folders.
When designing transactional email templates like password resets or order confirmations.
When implementing email capture forms that require legal consent tracking.
When auditing existing email templates for accessibility and compliance.

Advantages

Reduces the risk of legal penalties by providing clear compliance guidelines.
Improves email deliverability by standardizing authentication and list hygiene.
Ensures emails are accessible to all users, including those using assistive technology.
Provides a clear architectural path for building production-ready email systems.
Helps distinguish between transactional and marketing email strategies to optimize engagement.

Usage examples

“What are the legal requirements for sending marketing emails to users in the EU versus the US?”: The agent provides a comparison of GDPR and CAN-SPAM, highlighting the need for explicit opt-in consent for GDPR and the requirement for physical addresses and opt-out mechanisms for CAN-SPAM.
“How do I make my transactional email templates accessible for screen readers?”: The agent outlines specific HTML requirements, such as setting lang/dir attributes, using role='presentation' for layout tables, and ensuring proper heading hierarchy.
“My emails are going to spam. What should I check first?”: The agent directs the user to the deliverability reference to verify DNS authentication (SPF, DKIM, DMARC) and check for common configuration issues.

Install

Download the skill as a ZIP:
https://autogineer.com/agent-skills/resend/email-best-practices/download

Unzip it into the cross-client skills folder of your project:

mkdir -p .agents/skills && unzip email-best-practices.zip -d .agents/skills

Documentation by Resend

Guidance for building deliverable, compliant, user-friendly emails.

Architecture Overview

[User] → [Email Form] → [Validation] → [Double Opt-In]
                                              ↓
                                    [Consent Recorded]
                                              ↓
[Suppression Check] ←──────────────[Ready to Send]
        ↓
[Idempotent Send + Retry] ──────→ [Email API]
                                       ↓
                              [Webhook Events]
                                       ↓
              ┌────────┬────────┬─────────────┐
              ↓        ↓        ↓             ↓
         Delivered  Bounced  Complained  Opened/Clicked
                       ↓        ↓
              [Suppression List Updated]
                       ↓
              [List Hygiene Jobs]

Quick Reference

Need to...	See
Set up SPF/DKIM/DMARC, fix spam issues	Deliverability
Build password reset, OTP, confirmations	Transactional Emails
Plan which emails your app needs	Transactional Email Catalog
Build newsletter signup, validate emails	Email Capture
Send newsletters, promotions	Marketing Emails
Ensure CAN-SPAM/GDPR/CASL compliance	Compliance
Decide transactional vs marketing	Email Types
Handle retries, idempotency, errors	Sending Reliability
Process delivery events, set up webhooks	Webhooks & Events
Manage bounces, complaints, suppression	List Management
Make emails accessible (screen readers, alt text, contrast)	Accessibility

Start Here

New app? Start with the Catalog to plan which emails your app needs (password reset, verification, etc.), then set up Deliverability (DNS authentication) before sending your first email.

Spam issues? Check Deliverability first—authentication problems are the most common cause. Gmail/Yahoo reject unauthenticated emails.

Marketing emails? Follow this path: Email Capture (collect consent) → Compliance (legal requirements) → Marketing Emails (best practices).

Production-ready sending? Add reliability: Sending Reliability (retry + idempotency) → Webhooks & Events (track delivery) → List Management (handle bounces).

Accessibility? Most emails fail basic accessibility checks. See Accessibility for lang/dir, presentational tables, headings, alt text, <title>, and contrast.

Files

ATTRIBUTION.mdAdded by AutoGineer904 B
LICENSELicence file added by AutoGineer1.0 KiB
SKILL.md3.9 KiB
references/accessibility.md9.3 KiB
references/compliance.md4.1 KiB
references/deliverability.md3.3 KiB
references/email-capture.md3.4 KiB
references/email-types.md5.7 KiB
references/list-management.md4.5 KiB
references/marketing-emails.md3.2 KiB
references/sending-reliability.md4.5 KiB
references/transactional-email-catalog.md10.1 KiB
references/transactional-emails.md2.4 KiB
references/webhooks-events.md4.2 KiB

references/compliance.md

Email Compliance

Legal requirements for email by jurisdiction. Not legal advice—consult an attorney for your specific situation.

Quick Reference

Law	Region	Key Requirement	Penalty
CAN-SPAM	US	Opt-out mechanism, physical address	$53k/email
GDPR	EU	Explicit opt-in consent	€20M or 4% revenue
CASL	Canada	Express consent, opt-out mechanism	$1M (individual) to $10M (organization) CAD

CAN-SPAM (United States)

Requirements:

Accurate header info (From, To, Reply-To)
Non-deceptive subject lines
Physical mailing address in every email
Clear opt-out mechanism
Honor opt-out within 10 business days

Transactional emails: Can send without opt-in if related to a transaction and not promotional.

Requirements:

Explicit opt-in consent (not pre-checked boxes)
Consent must be freely given, specific, informed
Easy to withdraw consent (as easy as giving it)
Right to access data and deletion ("right to be forgotten")
Process unsubscribe immediately

Consent records: Document who, when, how, and what they consented to.

Transactional emails: Can send based on contract fulfillment or legitimate interest.

CASL (Canada)

Consent types:

Express consent: Explicit opt-in (ideal)
Implied consent: Existing business relationship (2 years) or inquiry (6 months)

Requirements:

Clear sender identification that will be valid for 60 days after send
Unsubscribe functional for 60 days after send
Process unsubscribe no later than 10 business days
Keep consent records 3 years after expiration

Other Regions

Region	Law	Key Points
Australia	Spam Act 2003	Consent required, honor unsubscribe within 5 days
UK	PECR + GDPR	Same as GDPR
Brazil	LGPD	Similar to GDPR, explicit consent for marketing

Unsubscribe Requirements Summary

Law	Timing	Notes
CAN-SPAM	10 business days	Must work 30 days after send
GDPR	Immediately	Must be as easy as opting in
CASL	10 business days	Must work 60 days after send

Universal best practices: Prominent link, one-click when possible, no login required, free, confirm action.

List-Unsubscribe Header (Required for Bulk Senders)

Gmail, Yahoo, and Microsoft require List-Unsubscribe headers. Without them, bulk emails may be rejected or spam-filtered.

Required headers:

headers: {
  'List-Unsubscribe': '<https://example.com/unsubscribe>',
  'List-Unsubscribe-Post': 'List-Unsubscribe=One-Click',
}

Your unsubscribe endpoint must:

Accept POST requests — return 200 or 202 with a blank page
Display standard unsubscribe page for GET requests
Stop sending within 48 hours of the request

Managing preferences vs Unsubscribe from all

Most legistlations require a one-click unsubscribe. Managing preferences is a nice-to-have and can lead to lower unsubscribe rate but doesn't replace Unsubscribe. If possible, offer both.

Record:

Email address
Date/time of consent
Method (form, checkbox)
What they consented to
Source (which page/form)

Storage: Database with timestamps, audit trail of changes, link to user account.

Data Retention

Law	Requirement
GDPR	Keep only as long as necessary, delete when no longer needed
CASL	Keep consent records 3 years after expiration

Best practice: Have clear retention policy, honor deletion requests promptly, review and clean regularly.

Privacy Policy Must Include

What data you collect
How you use data
Who you share data with
User rights (access, deletion)
How to contact about privacy

International Sending

Best practice: Follow the most restrictive requirements (usually GDPR) to ensure compliance across all regions.

Email Capture - Implement consent forms and double opt-in
Marketing Emails - Consent and unsubscribe requirements
List Management - Handle unsubscribes and deletion requests

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Security

No issues found by our static scan· No issues found

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

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Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download email-best-practices.zip

From the author

AutoGineer summary

What it does

When to use it

Advantages

Usage examples

Install

Documentation by Resend