WordPress powers over 40% of the web. Its wp_mail() function (PHPMailer) accepts any SMTP relay via plugins (WP Mail SMTP, FluentSMTP), and a huge plugin ecosystem handles newsletters, forms, and eCommerce email. The canonical SMTP-plugin target.
Install WP Mail SMTP, point it at smtp.mailkite.dev, done. See /docs/integrations/wordpress.
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=WordPress Point a domain, set one SMTP endpoint, send your first email in minutes. Unlimited domains, no credit card.