Transactional email resources

Plain-language explanations of transactional email, deliverability, SPF, DKIM and DMARC, written for people who have to implement them.

SMTP vs email API
SMTP and an email API both hand a message to a provider. How they differ in errors, speed, security and fit, how to choose, and what Inboxili supports today.
SPF, DKIM and DMARC explained, with the records you will actually publish
SPF authorises sending servers, DKIM signs messages, DMARC ties them to your From domain and sets a policy. How each works, how they fail, and the exact records Inboxili asks for.
Transactional email deliverability checklist
Why transactional emails land in spam or arrive late, and what you control: domain authentication, sending identity, content, bounce handling and monitoring.
Transactional vs marketing email
Transactional email is triggered by a user's action and expected by them; marketing email is sent to promote. How they differ in law, deliverability and infrastructure, and why to keep them apart.