There still is an active advisory from EU-Cert CERT-EU - SMTP Smuggling Vulnerability in CISCO Secure Email Gateway (europa.eu) mentioning this flaw (no working SPF, DMARC, DKIM check for the smuggled mail) if having the "clean" option under "Network...
It is 2023, five years after the release of the standard, and a "security" appliance cannot do TLS 1.3. An indictment, no one has to wonder why such products are often called snake oil.A growing number of mail servers only support TLS 1.3 for encrypt...