What is MTA-STS? A Plain-English Guide
MTA-STS (Mail Transfer Agent Strict Transport Security) lets your domain require that incoming mail be delivered over encrypted TLS, preventing downgrade attacks. It is published via a DNS record and an HTTPS policy file.
Why it matters for deliverability
Understanding MTA-STS is part of transport security that mailbox providers increasingly expect. Get it right and more of your mail reaches the inbox; get it wrong and even legitimate mail can be filtered.
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