qmail has a strong historical security reputation but many deployments depend on patches and external tooling.
- Restrict SMTP listener access based on role (MX vs submission).
- Prevent open relay configuration.
- Run qmail components as dedicated low-privilege users.
¶ TLS and Modern Mail Stack
- Use qmail distributions/patches that support modern TLS.
- Validate certificates and key file permissions.
- Integrate SPF/DKIM/DMARC with complementary tooling.
- Track maintenance status of chosen qmail variant.
- Audit applied patches and third-party add-ons.
- Monitor queue behavior and abuse indicators.