Ensure SMTP AUTH is disabled
Why This Matters
SMTP AUTH is a legacy authentication protocol that lacks modern security protections like multifactor authentication and Conditional Access. Keeping it enabled exposes your organization to credential-based attacks, including password spraying and brute force attempts. Since almost all modern email clients can connect to Exchange Online without SMTP AUTH, there is no reason to leave this attack surface open.
What Aether365 Checks
This check verifies that SMTP AUTH is disabled at the organization level in Exchange Online. It appears in the Aether365 dashboard under microsoft-365 checks as M365.2129 and will flag a finding if the setting "Turn off SMTP AUTH protocol for your organization" is not enabled.