Maileon SMTP accounts can add and save a mailing domain even when its A record or MX record does not point to Maileon. Tracking is deactivated for a domain without the Maileon A record, and the interface warns explicitly about every missing record instead of blocking the setup. SPF and DKIM records remain required. Use case: Send transactional emails from newsletter@company.com while the A and MX records of the domain continue to serve the website and the corporate mailboxes.