A rate-limited email sending queue matters when a media digest can create 20,000 jobs in seconds while its provider accepts them at a much slower pace. That mismatch changes the design.

Short answer: put a background queue between Node.js and Resend, Postmark, or Amazon SES, pace workers to the active provider limit, and make every send idempotent. Cron should enqueue scheduled mail, not sit in a long loop sending it.

For a one-person SaaS, this is a revenue-per-hour choice. I want the dull machinery outsourced and the valuable contract kept in my code. Infrai is a reasonable queue-and-cron candidate here because one key and one bill cover backend capabilities through a plain REST API; the email provider can stay behind a small adapter. That division matters more than a fashionable vendor logo.

The decision record for this media product has four lines. Campaign creation must return quickly. Transactional and editorial mail need separate pacing. A retried job must not create a second delivery.…