Glossary
Transactional email
Mail the recipient triggered: OTPs, receipts, resets, alerts.
Transactional email is sent in response to a user action or system event: one-time passcodes, verification links, password resets, receipts, shipping alerts. It is the opposite of bulk/marketing email: expected, high-engagement, and time-sensitive.
Because recipients want it, transactional mail earns the best deliverability — provided authentication (SPF, DKIM, DMARC) is correct and bounces are suppressed. Mixing it with marketing blasts on shared infrastructure is how reputations die.
In Calder: Sending with Calder