A list of approved IP addresses for sending mail SHALL be maintained
Part of CISA · Exchange Online · Email authentication · All checks
Invoke-Maester -TestId CISA.MS.EXO.2.1Overview
Section titled “Overview”This test is deprecated by CISA as of May 2024 and will always be skipped. The content below is retained as a historical archive and will be removed in a future version.
MS.EXO.2.1v1 was removed because it is not a security configuration that can be audited; it acts as an implementation step for MS.EXO.2.2. Maintaining the list of approved IP addresses has been incorporated into the implementation guidance for MS.EXO.2.2 and removed as a standalone policy. See CISA SCuBA Removed Policies — MS.EXO.2.1v1.
A list of approved IP addresses for sending mail SHALL be maintained.
Rationale: Failing to maintain an accurate list of authorized IP addresses may result in spoofed email messages or failure to deliver legitimate messages when SPF is enabled. Maintaining such a list helps ensure that unauthorized servers sending spoofed messages can be detected, and permits message delivery from legitimate senders.
Remediation action
Section titled “Remediation action”- Identify any approved senders specific to your agency.
- Perform regular review of SPF record and update as necessary.
- Additionally, see External DNS records required for SPF for inclusions required for Microsoft to send email on behalf of your domain.
Related links
Section titled “Related links”- Exchange admin center - Accepted domains
- CISA 2 Sender Policy Framework - MS.EXO.2.1v1
- CISA ScubaGear Rego Reference
Details
Section titled “Details”Every attribute of this check
| Field | Value |
|---|---|
| Test ID | CISA.MS.EXO.2.1 |
| Severity | Medium |
| Suite | CISA |
| Product | Exchange Online |
| Feature | Email authentication |
| Area | Email and collaboration protection |
| Resource type | Domain |
| User impact | Low |
| Implementation cost | Medium |
| MITRE ATT&CK | T1684.002 Email Spoofing |
| Supports benchmark | CISA SCuBA Secure Configuration Baselines for Microsoft 365 (version ScubaGear main, 2026-10-11), requirement MS.EXO.2.1 |
| Criticality | SHALL |
| Supports controls | cisa-scuba:MS.EXO.2.1 |
| PowerShell test | Test-MtCisaSpfRestriction |
| Services | Graph |
| Lifecycle | Deprecated |
Source
Section titled “Source”- Test:
tests/cisa/exchange/Test.CISA.MS.EXO.2.1.ps1 - Documentation:
tests/cisa/exchange/Test.CISA.MS.EXO.2.1.md