Sender Compliance Check

Since February 2024 Google and Yahoo, and since May 2025 Microsoft (Outlook.com, Hotmail, Live), reject or junk mail from domains that do not meet their sender requirements. The rules apply in full to anyone sending 5,000+ messages a day, but SPF, DKIM and DMARC are now expected of everyone. This check verifies what is visible in DNS, and if you paste the headers of a real message it verifies the rest.