EC
250
SMTPINFOCriticalSuccessful DeliveryHIGH confidence

Requested mail action okay, completed

What this means

The 250 code is the most common success code, indicating that the server has accepted and completed the requested action. It is sent after commands like `EHLO`, `MAIL FROM`, and `RCPT TO` have been successfully processed.

Why it happens
  1. 1The `EHLO` command was accepted.
  2. 2The `MAIL FROM` address was valid and accepted.
  3. 3The `RCPT TO` address was valid and accepted.
  4. 4The email data was successfully received after the `DATA` command.
How to reproduce

A client specifies a valid recipient, and the server confirms it can accept mail for that address.

trigger — this will error
trigger — this will error
RCPT TO:<recipient@example.com>
250 2.1.5 OK

expected output

250 OK

Fix

Verify 250 after each MAIL FROM and RCPT TO before proceeding

WHEN In SMTP client code — every critical command must return 250

Verify 250 after each MAIL FROM and RCPT TO before proceeding
MAIL FROM:<sender@example.com>
250 2.1.0 OK
RCPT TO:<recipient@example.com>
250 2.1.5 OK
DATA
354 ...
.
250 2.0.0 OK: queued

Why this works

Each command must be acknowledged with 250 before the next is issued (unless pipelining is negotiated). A non-2xx reply at any step means that step failed.

What not to do

✕ Assume 250 after DATA means the email was delivered to the recipient

250 means the server accepted and queued the message. Delivery to the final recipient may still fail — the server will send an NDR bounce if it does.

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