There is an SMTP bounce back problem when sending to clients:

Subject: Mail delivery failed: returning message to sender

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:

  [email protected]
    SMTP error from remote mail server after end of data:
    host coct-edge-004.capetown.gov.za []:
    550 5.7.1 Message rejected due to content restrictions
  [email protected]
    SMTP error from remote mail server after end of data:
    host coct-edge-004.capetown.gov.za []:
    550 5.7.1 Message rejected due to content restrictions

------ This is a copy of the message, including all the headers. ------
------ The body of the message is 41054 characters long; only the first
------ 16384 or so are included here.

Return-path: <[email protected]>
Received: from 41-134-213-41.dsl.mweb.co.za ([] helo=Vitcptex01.corpcomputers.co.za)
    by relay09.smp.mweb.co.za with esmtp (Exim 4.77)
    id 1Sgbs9-0000yC-U6; Mon, 18 Jun 2012 15:20:02 +0200
Received: from VITCPTEX01.corpcomputers.co.za ([]) by Vitcptex01
 ([]) with mapi; Mon, 18 Jun 2012 15:20:01 +0200
From: Karen Alexander <[email protected]>
To: Melisse Fernandez <[email protected]>, Tracy-Lee Petersen
    <[email protected]>
CC: Kauthar Londt <[email protected]>, All_Technical
    <[email protected]>
Date: Mon, 18 Jun 2012 15:20:00 +0200
Thread-Topic: HP PRINTER
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Message-ID: <A40EFFB628E7094B9FE43B3D90090B09D1364509F7@Vitcptex01>
References: <DDFEEF88E36AB5418BB42BFDFA352D0D65E960C7@CBD-CIVIC-XMB01.capetown.gov.za>
In-Reply-To: <47B3CDFC4522FC46B5E5511926A5111665E63DC8@CBD-CIVIC-XMB01.capetown.gov.za>
Accept-Language: en-US, en-ZA
Content-Language: en-US
X-MS-Has-Attach: yes
acceptlanguage: en-US, en-ZA
Content-Type: multipart/related;
MIME-Version: 1.0

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5 Answers 5


The message bounces back because of a content restriction on the server

550 5.7.1 Message rejected due to content restrictions

I don't know what you are sending but the server doesn't like it.


It seems that the mail contains some text or attachment that the recipient doesn't allow. You'll have to ask them to hear what it is that they don't allow. Normally when this happens, it's because the recipient doesn't allow special file types, eg. executable.

Have you tried to send a test mail, just without any attachments or very much text?


The target mail server doesn't like your message content,

550 5.7.1 Message rejected due to content restrictions

Normally, 550 means the recipient mail box doesn't exist or can't be written to, but whatever MTA you're talking to here is using it to tell you about a policy based rejection.

A quick search on the web shows a well known product combination (Exchange + Anti-malware scanners) which generate this message, sometimes giving false positives, although it doesn't mean they're false in your case. Whatever the cause, the action is to speak to the recipient mail server owners.


Says in the bounce it was rejected because:

550 5.7.1 Message rejected due to content restrictions

Without knowing more context, it could be due to your message being seen as spam, it could be because of interpretation of rules and the receiving site doesn't like a hyphen in a domain name (http://social.technet.microsoft.com/Forums/en-US/forefrontexchange/thread/2fb91e96-8d07-4700-ae2e-bb0a01dae5e1) or a period in the "wrong" place, could be a number of things.

You may have to work with a recipient's IT department if this is a legitimate mail to find the root cause of the bounce. If this is a glitch with their spam filtering the recipient(s) could be losing other emails.


The 550 5.7.1 has to due with a specific error code related to email content. Something within your emails, which is triggering that servers rules, is related to the content of the email. Either the text within the body, the subject, any images, links, etc.

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