RHEL 10 must be configured to prevent unrestricted mail relaying.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-280999 | SRG-OS-000095-GPOS-00049 | RHEL-10-200692 | SV-280999r1165352_rule | 2026-03-11 | 1 |
Description
If unrestricted mail relaying is permitted, unauthorized senders could use this host as a mail relay to send spam or for other unauthorized activity.
ℹ️ Check
Note: If postfix is not installed, this is not applicable.
Verify RHEL 10 is configured to prevent unrestricted mail relaying with the following command:
$ postconf -n smtpd_client_restrictions
smtpd_client_restrictions = permit_mynetworks,reject
If the "smtpd_client_restrictions" parameter contains any entries other than "permit_mynetworks" and "reject", and the additional entries have not been documented with the information system security officer, this is a finding.
✔️ Fix
Configure RHEL 10 so that the postfix configuration file restricts client connections to the local network with the following command:
$ sudo postconf -e 'smtpd_client_restrictions = permit_mynetworks,reject'