---
title: "NET-MAIL-003 Postfix VRFY Command Enabled"
canonical: https://openvapt.com/checks/NET-MAIL-003.html
html: https://openvapt.com/checks/NET-MAIL-003.html
site: OpenVAPT, https://openvapt.com/
license: OpenVAPT Source-Available Licence 1.3, https://openvapt.com/legal/licence-text.html
modified: 2026-10-14
version: 0.1.0-alpha.6
---

# NET-MAIL-003 Postfix VRFY Command Enabled

disable_vrfy_command is not yes, so anyone who connects can ask the server whether a mailbox exists.

- Domain: Network
- Severity: Low
- Control category: Information Exposure
- Fix effort: low
- CVSS v3.1 vector: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N`
- CIS Controls v8: 4.1
- NIST CSF 2.0: PR.PS-01
- CWE: CWE-204
- OWASP Top 10 2021: A05:2021
- NIST SP 800-53 Rev. 5: CM-7, SI-11
- Benchmark topic: Mail server user enumeration (topic only, no benchmark text)

## Why It Matters

VRFY lets a sender enumerate valid addresses one by one, which feeds spam lists and targeted phishing. Legitimate mail flow never needs it.

## How It Detects

Reads main.cf for disable_vrfy_command. Fails when absent (default no) or set to no, unless inet_interfaces is loopback only (localhost, loopback-only or loopback addresses): then no network client can connect and the result is Pass with a note.

## How to Fix

Add  disable_vrfy_command = yes  to main.cf and postfix reload.

## How to Verify

```
postconf disable_vrfy_command  should print yes; an authorised  VRFY postmaster  over a local SMTP session should return 502.
```

## Learn the Theory

- [P19 Database, Mail and DNS Hardening](https://openvapt.com/academy/p19.md)

## References

- [Postfix, disable_vrfy_command](https://www.postfix.org/postconf.5.html#disable_vrfy_command)
- [RFC 5321, Simple Mail Transfer Protocol, section 7.3](https://www.rfc-editor.org/rfc/rfc5321.html#section-7.3)

## Source Code

https://github.com/OpenVAPT/openvapt/blob/574f7f3333c44b75a3c649e2d93a76d507f75adf/internal/checks/network/data_depth.go

Run it: `openvapt scan --only NET-MAIL-003`. Read it offline: `openvapt explain NET-MAIL-003`.

---

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