The email landscape has fundamentally changed β and in 2026, there is no ambiguity left:
DMARC is no longer optional. It is enforced.
Over the past two years, the worldβs largest mailbox providers β Google, Yahoo, and Microsoft β have implemented strict authentication requirements. Today, any domain sending bulk email must have properly configured SPF, DKIM, and DMARC, or risk outright rejection. [mailcop.net], [redsift.com]
This shift marks the end of the βopen email eraβ and the beginning of a trust-based ecosystem where authentication is mandatory.