Google now blocks spoofed emails for better phishing protection

Google is enforcing stricter Gmail policies for bulk senders, requiring SPF/DKIM/DMARC authentication, one-click unsubscribe with 2-day processing, spam rates below 0.3%, and non-impersonating From headers, with temporary errors now and gradual rejection of non-compliant traffic beginning April 2024 (accelerating for domains used since Jan 1, 2024) to curb spam, phishing, and malware.