Drupal Mail System Configuration

Quick Reference

Local Testing (DDEV Mailpit)

Working configuration for HTML emails in Mailpit:

# mailsystem.settings
defaults:
  sender: php_mail
  formatter: mailchimp_transactional_mail

Enable/disable notifications:

# Check if notifications are disabled
ddev drush state:get my_notifications.disabled

# Enable notifications (for local testing)
ddev drush state:set my_notifications.disabled 0

# Disable notifications (to stop local emails)
ddev drush state:set my_notifications.disabled 1

View Mailpit:

• URL: https://<project>.ddev.site:8026
• Or run: ddev mailpit

Production Configuration

Mailchimp Transactional (Mandrill) for sending:

# mailsystem.settings
defaults:
  sender: mailchimp_transactional_mail
  formatter: mailchimp_transactional_mail

Mail System Architecture

Key Concepts

1. Sender: The plugin that actually sends the email (SMTP, PHP mail(), API)
2. Formatter: The plugin that formats the email body (converts HTML, wraps content)
3. Content-Type Header: Must be set to text/html for HTML rendering

Plugin Combinations

HTML Email Requirements

Content-Type Header

Critical: Module must set Content-Type header in hook_mail_alter():

/**
 * Implements hook_mail_alter().
 */
function my_notifications_mail_alter(&$message) {
  if ($message['module'] === 'my_notifications') {
    $message['headers']['Content-Type'] = 'text/html; charset=UTF-8';
  }
}

Without this, HTML renders as plain text even with correct formatter.

Message Template Format

Config entity format (message.template.*.yml):

text:
  -
    value: |-
      Subject line with [tokens]

      <p style="margin: 0 0 16px 0; color: #333;">HTML body content</p>
    format: full_html

Key points:

• First line = email subject (extracted, stripped of HTML)
• Rest = HTML email body
• Use inline styles (email clients strip <style> tags)
• format: full_html enables HTML rendering

Configuration Commands

Check Current Config

# View mail system settings
ddev drush cget mailsystem.settings

# View notification plugin settings
ddev drush cget my_notifications.settings

# Check global disable state
ddev drush state:get my_notifications.disabled

Switch Between Local and Production

For local testing:

# Enable HTML email capture in Mailpit
ddev drush cset mailsystem.settings defaults.sender php_mail -y
ddev drush cset mailsystem.settings defaults.formatter mailchimp_transactional_mail -y
ddev drush state:set my_notifications.disabled 0
ddev drush cr

Reset to production:

ddev drush cset mailsystem.settings defaults.sender mailchimp_transactional_mail -y
ddev drush cset mailsystem.settings defaults.formatter mailchimp_transactional_mail -y
ddev drush state:set my_notifications.disabled 1
ddev drush cr

Testing Notifications

Test Commands

Give your notification module drush test commands so each template can be fired on demand, e.g.:

# Test entity deleted notification
ddev drush my-notifications:test-entity-deleted

# Test entity updated notification
ddev drush my-notifications:test-entity-updated

# Test comment notification
ddev drush my-notifications:test-comment

# Test group invitation
ddev drush my-notifications:test-invitation

Verify Email in Mailpit

1. Open https://<project>.ddev.site:8026
2. Check Headers tab: Content-Type: text/html; charset=UTF-8
3. Check HTML tab: Proper styled rendering
4. Check Text tab: Plain text fallback

Mailpit API

# List recent messages
curl -sk "https://<project>.ddev.site:8026/api/v1/messages" | jq '.messages[:3]'

# Get specific message with HTML
curl -sk "https://<project>.ddev.site:8026/api/v1/message/{ID}" | jq '{Subject, HTML}'

# Delete all messages
curl -sk -X DELETE "https://<project>.ddev.site:8026/api/v1/messages"

Troubleshooting

No Emails Appearing

1. Check global disable state:

   ddev drush state:get my_notifications.disabled
   # If TRUE, run: ddev drush state:set my_notifications.disabled 0
   

2. Check sender plugin:

   ddev drush cget mailsystem.settings defaults.sender
   # For Mailpit: should be php_mail
   

3. Check DDEV is running:

   ddev describe | grep -i mail
   

4. Test raw PHP mail:

   ddev exec "php -r \"mail('test@example.com', 'Test', 'Body');\""
   # Should appear in Mailpit immediately
   

HTML Not Rendering (Shows Raw Tags)

1. Check formatter plugin:

   ddev drush cget mailsystem.settings defaults.formatter
   # Should be mailchimp_transactional_mail for HTML
   

2. Check Content-Type header in hook_mail_alter():

   grep -r "Content-Type.*text/html" web/modules/custom/
   

3. Check template format:

   grep "format:" config/default/message.template.*.yml
   # Should show: format: full_html
   

Emails Sending to Production

1. Check sender plugin:

   ddev drush cget mailsystem.settings defaults.sender
   # If mailchimp_transactional_mail, emails go to real addresses!
   

2. Switch to local capture:

   ddev drush cset mailsystem.settings defaults.sender php_mail -y
   

Module Dependencies

• mailsystem: Routes mail through configured plugins
• mailchimp_transactional: Provides Mandrill integration
• message: Provides template-based message entities
• my_notifications: Custom notification system

File Locations

• Mail config: config/default/mailsystem.settings.yml
• Notification settings: config/default/my_notifications.settings.yml
• Message templates: config/default/message.template.*.yml
• Notification processor: web/modules/custom/my_notifications/src/Plugin/QueueWorker/NotificationProcessor.php
• Mail alter hook: web/modules/custom/my_notifications/my_notifications.module

Apply to Files

• config/default/mailsystem.settings.yml
• config/default/my_notifications.settings.yml
• config/default/message.template.*.yml
• web/modules/custom/my_notifications/**/*.php
• web/modules/custom/my_notifications/*.module