252
SMTPINFOCriticalSuccessful DeliveryHIGH confidence

Cannot VRFY user, but will accept message and attempt delivery

What this means

The 252 code is a cautious success, where the server cannot verify the recipient's existence but agrees to accept the email and try delivering it. This is often used to prevent address harvesting by blocking `VRFY` requests.

Why it happens
  1. 1The server has the `VRFY` command disabled for security reasons.
  2. 2The server is configured to accept all mail for a domain and sort it out later.
  3. 3It's a 'catch-all' address scenario.
How to reproduce

A client attempts to verify an address using the VRFY command, but the server has it disabled.

trigger — this will error
trigger — this will error
VRFY <some-user@example.com>
252 2.1.5 Cannot VRFY user

expected output

252 Cannot VRFY user

Fix

Treat 252 as a positive reply and proceed with sending

WHEN When the server responds to VRFY with 252

Treat 252 as a positive reply and proceed with sending
VRFY <user@example.com>
252 Cannot VRFY; will accept and attempt delivery
# Proceed with MAIL FROM / RCPT TO / DATA

Why this works

252 means the server will attempt delivery. This is intentional behaviour to prevent address harvesting. Clients should proceed with the normal send sequence.

What not to do

Use VRFY to validate addresses before sending

Most production servers disable VRFY and always return 252 to prevent spam harvesters from probing for valid addresses. The response tells you nothing about address validity.

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