Short answer: for a beginner SaaS sending marketplace order notifications, an API-first email provider is viable when it offers domain verification, suppression controls, and queryable delivery events; choose an established alternative such as SendGrid, Resend, or Postmark instead when SMTP relay compatibility or real-time webhook automation is mandatory.
The hard trade-off is delivery reliability versus integration flexibility. A direct send API can support healthy, branded transactional email in US and EU markets, but an accepted API request isn't proof that a seller saw the message. Domain authentication, suppression checks, and event review have to be part of the same operational path. The catch is that a pull-only event model adds detection delay, while the absence of SMTP relay makes some migrations more expensive.
For a marketplace order alert, I would optimize for evidence, not for the prettiest send call.
Evidence first.
The order-alert reliability contract starts before sending
