Discover how the 2025 changes to NCSC Mail Check will impact UK public sector organizations and learn strategies for maintaining robust protection against phishing and spoofing.
A DMARC policy allows domain owners to specify how email receivers should handle emails that fail authentication checks (SPF and DKIM) - none, quarantine or reject.
The “550 SPF check failed” message is common error prompt that maybe triggered by an absent or invalid SPF record in the sender’s DNS, or third-party spam filters.
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