DMARC alignment
The domain match DMARC checks after SPF or DKIM passes.
DMARC does not only ask whether SPF or DKIM passed. It asks whether the passing domain aligns with the visible From domain. SPF alignment compares the Return-Path domain to the From domain. DKIM alignment compares the d= signing domain to the From domain.
reading this as teams choosing a transactional API
Judged purely as an API. What the request contract guarantees on retry, how complete the webhook event coverage is, whether suppressions are readable and writable programmatically, and how much the message log retains when something needs debugging in production.
Applied to dmarc alignment, that means weighing idempotency keys, webhook coverage, event stream, and operating track record ahead of the rest, against high-frequency programmatic sends where a missed delivery is a product failure.