The Exchange Simple Mail Transfer Protocol (SMTP) Sender filter must be enabled.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-221248	SRG-APP-000261	EX16-ED-000520	SV-221248r961161_rule	2024-12-06	2

Description
Email system availability depends in part on best practices strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts. Filters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Filters for messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective. Failure to enable the filter will result in no action taken. This setting should always be enabled.

Description

Email system availability depends in part on best practices strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts. Filters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Filters for messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective. Failure to enable the filter will result in no action taken. This setting should always be enabled.

ℹ️ Check
This requirement is N/A for SIPR enclaves. This requirement is N/A if the organization subscribes to EEMSG or other similar DoD enterprise protections for email services. Open the Exchange Management Shell and enter the following command: Get-SenderFilterConfig \| Select Name, Enabled If the value of "Enabled" is not set to "True", this is a finding.

✔️ Fix
Open the Exchange Management Shell and enter the following command: Set-SenderFilterConfig -Enabled $true