On Feb. 1, 2024, Google and Yahoo began enforcing new requirements for bulk email senders defined as those sending more than 5,000 messages to Gmail addresses in one day, according to [MarTech](https://martech.org/new-rules-for-bulk-email-senders-from-google-yahoo-what-you-need-to-know/).
All three providers require bulk senders to implement SPF to identify authorized email servers, DKIM to add digital signatures verifying authorized senders, and DMARC to specify actions on authentication...