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Region Selection

When to Use

Use this when creating a Mailgun account or adding a sending domain. The region choice affects where email content is stored and which API endpoint your Drupal site hits. The choice is not retroactive — wrong-region keys won't authenticate.

Decision

Region API host SMTP host Use When
US api.mailgun.net smtp.mailgun.org Default. US data residency acceptable. Lower latency from US servers.
EU api.eu.mailgun.net smtp.eu.mailgun.org GDPR data-residency requires EU storage of email content/metadata.

Pattern

Picking a region: 1. Default to US unless legal/contractual requirement specifies EU 2. If GDPR scope: pick EU at account/domain creation 3. Decision is per-domain — you can have US and EU domains in the same Mailgun account, but each needs its own API key

Setting region in drupal/mailgun (settings.php):

$config['mailgun.settings']['api_endpoint'] = 'https://api.eu.mailgun.net';

Setting region in Symfony Mailer DSN:

mailer_dsn:
  scheme: mailgun+api
  host: default
  user: '{{ MAILGUN_API_KEY }}'
  password: 'mg.example.com'
  options:
    region: eu

Or via Admin UI: /admin/config/services/mailgun → "API endpoint" dropdown.

Common Mistakes

  • Wrong: Generating an API key on the US dashboard but configuring Drupal to use api.eu.mailgun.net → Right: 401 Unauthorized — region mismatch is the #1 support ticket. Match endpoint to where the domain was created.
  • Wrong: Assuming you can switch regions later → Right: Effectively no — the domain belongs to one region; to migrate, recreate the domain in the other region, redo DNS, regenerate keys.

See Also