Drupal is an enterprise open-source CMS. It uses PHP mail() or an SMTP module (and Symfony Mailer in modern versions) for transactional email, with modules for newsletters and ESP integrations.
Configure Drupal's SMTP module to MailKite. See /docs/integrations/drupal.
Read the full setup guideA minimal, copy-paste starter. Swap in your own domain and API key.
# Any app that accepts an SMTP server works with MailKite
MAIL_HOST=smtp.mailkite.dev
MAIL_PORT=587 # STARTTLS (or 465 for TLS)
MAIL_ENCRYPTION=tls
MAIL_USERNAME=mailkite # username is ignored
MAIL_PASSWORD=mk_live_... # your MailKite API key
MAIL_FROM_ADDRESS=you@yourdomain.com # on a verified domain
MAIL_FROM_NAME=Drupal Point a domain, set one SMTP endpoint, send your first email in minutes. Unlimited domains, no credit card.