---
title: "Email error 551"
description: "A 551 email error is normally ecountered when there is an attempted delivery to a mail server that doesn't handle mail for the specified recipient. You should receive a bounce-back message from the..."
url: https://www.inmotionhosting.com/support/email/email-error-551/
date: 2012-10-26
modified: 2021-08-16
author: "InMotion Hosting Contributor"
categories: ["Email", "Website Error Numbers"]
type: post
lang: en
---

# Email error 551

A **551 email error** is normally ecountered when there is an attempted delivery to a mail server that doesn’t handle mail for the specified recipient.

You should receive a bounce-back message from the server with a variation of **email error 551** in the subject, and the body should contain your original message that you attempted to deliver.

## Example bounce-back message

Return-path: <>
Envelope-to: **sender@example.com**
Delivery-date: Thu, 25 Oct 2012 11:19:59 -0700
Received: from mailnull by biz100.inmotionhosting.com with local (Exim 4.77)
id 1TRS2B-00033h-Fn
for **sender@example.com**; Thu, 25 Oct 2012 11:19:59 -0700
X-Failed-Recipients: **recipient@RemoteDomain.com**
Auto-Submitted: auto-replied
From: Mail Delivery System <Mailer-Daemon@biz100.inmotionhosting.com>
To: **sender@example.com**
Subject: [Mail delivery failed: returning message to sender](/support/email/mail-delivery-failed-returning-message-to-sender/)
Message-Id: <E1TRS2B-00033h-Fn@biz100.inmotionhosting.com>
Date: Thu, 25 Oct 2012 11:19:59 -0700

This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
 
**recipient@RemoteDomain.com**
SMTP error from remote mail server after RCPT TO:<**recipient@RemoteDomain.com**>:
host RemoteDomain.com [123.123.123.123]:
**551 not our customer**
 
—— This is a copy of the message, including all the headers. ——
 
Return-path: <**sender@example.com**>
Received: from bell.ca ([123.123.123]:42593 helo=Admin)
by biz100.inmotionhosting.com with esmtpa (Exim 4.77)
(envelope-from <**sender@example.com**>)
id 1TRS1q-0002fq-S4; Thu, 25 Oct 2012 11:19:39 -0700
Date: Fri, 26 Oct 2012 00:03:21 +0600
From: Sender <**sender@example.com**>
MIME-Version: 1.0
To: <**recipient@RemoteDomain.com**>
Subject: Meeting proposal

## Common variations of the 551 email error

- 551 5.1.1 recipient is not exist
- 551 5.1.1 user does not exist
- 551 Denied IVF
- 551 not our customer
- 551 recipient@RemoteDomain.com failed to route the address
- 551 <recipient@RemoteDomain.com>… User not locali
- 551 Relay request denied
- 551 This is not a relay host – mail must be to or from host domain.
- 551 Unknown user.
- 551 User not local. Authentication required for relay
- 551 User not local; please try <forward-path>

## Resolving a 551 email error bounceback

The 551 series of errors would typically be a hard bounce. For an in-depth review on the differences between soft and hard bounces, and general email bounceback reasons you can read [why does email bounce, bounceback, or error?](/support/email/email-bounce-bounceback-error/)

In our example bounce-back error above the reason the message has failed is because the server for **RemoteDomains.com **doesn’t control mail for the **recipient@RemoteDomain.com **e-mail address.