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553 email error is normally related to SMTP authentication not being used. Most mail servers require that you authenticate with a valid user on that system, before you're allowed to relay a remote message out. However some mail administrators will also using the 553 error if a user doesn't exist or for various other reasons as well.

You should receive a bounce-back message from the server with a variation of email error 553 in the subject, and the body should contain your original message that you attempted to deliver.

Example bounce-back message

Return-path: <>
Delivery-date: Mon, 14 Nov 2011 05:13:57 -0800
Received: from mailnull by with local (Exim 4.69)
id 1RPwMH-0008Q0-2H
for; Mon, 14 Nov 2011 05:13:57 -0800
Auto-Submitted: auto-replied
From: Mail Delivery System <>
Subject: Mail delivery failed: returning message to sender
Message-Id: <>
Date: Mon, 14 Nov 2011 05:13:57 -0800
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:
SMTP error from remote mail server after RCPT TO:<>:
host []:
553 5.7.1 Not an open relay, so get lost
------ This is a copy of the message, including all the headers. ------
Return-path: <>
Received: from chrisg6 by with local (Exim 4.69)
(envelope-from <>)
id 1RPwMG-0008Pm-5x
for; Mon, 14 Nov 2011 05:13:56 -0800
To: Recipient <>
X-Autorespond: On vacation
MIME-Version: 1.0
X-Loop: "On vacation" <>
Precedence: auto_reply
X-Precedence: auto_reply
From: "Sender" <>
Content-type: text/plain; charset=ansi_x3.110-1983
Subject: Email acknowledgement from Sender

Common variations of the 553 email error

  • 553 5.7.1 Not an open relay, so get lost
  • 553 Invalid user.
  • 553 message blocked, you are not authorized to send mail, authentication is required.
  • 553 Null Sender is not allowed.

  • 553 5.1.1 sorry, no mailbox here by that name.
  • 553 #5.1.8 Domain of sender address <> does not exist
  • 553 5.3.0 <>... Address does not exist
  • 553 5.3.0 <>... No such user
  • 553 5.3.0 <>... No such user here
  • 553 5.3.0 <>... User unknown, not local address
  • 553-Message filtered. Please see the FAQs section on spam\n
  • 553 <> does not have a mailbox here
  • 553 does not accept mail sent to
  • 553 sorry, no mail-box here by that name. (#5.1.1)
  • 553 sorry, no mailbox here by that name (#5.1.1)
  • 553 sorry, rcpt user invalid (#5.7.1)
  • 553 sorry, that domain isn't in my list of allowed rcpthosts
  • 553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)
  • 553 sorry, the recipient in not a valid user on this domain (#5.7.1)
  • 553 sorry, this recipient doesn't exist.
  • 553 sorry, this recipient is not in my validrcptto list (#5.7.1)
  • 553 sorry, your envelope sender is in my badmailfrom list (#5.7.1)
  • 553 Your email address is denied.

Resolving a 553 email error bounceback

The 553 series of errors would typically be a hard bounce, and usually your message is rejected right away. For a better understanding of a soft or hard bounce is, and general email bounceback errors you can read why does email bounce, bounceback, or error?

In our example bounce-back error above the reason the message has failed is because of a misconfigured auto-reply that has failed to first authenticate with the mail server before attempting to relay a reply to a message.

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n/a Points
2014-11-20 7:31 am

Your message did not reach some or all of the intended recipients.


      Subject:    Test

      Sent: 11/20/2014 4:36 PM




Mail was sending from ms outlook to gmail server.


The following recipient(s) cannot be reached:


      '**********' on 11/20/2014 4:36 PM

            Server error: '553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)'


Am usong ms outlook 2010... Pls suggest any solution ...

16,204 Points
2014-11-20 11:16 am
Hello Bhaskar,

Thank you for contacting us. I found a post regarding the 553 error on Microsoft's Official 2010 forums, where they suggest checking your email settings.

You can view your email settings in cPanel at any time.

Thank you,
n/a Points
2015-04-17 7:11 pm

Hi all

I have problem with my outlook 2007, this case i can connect to zimbra pop3 by outlook but cannot send out. i already use smtp port 25, 465 and 587 but still cannot send out the msg. this is the content msg "Send test e-mail message:   The server responded: 553 5.7.1 <"

can someone help me with this case!???


Best Regards

27,153 Points
2015-04-20 7:36 am
Hello Joseph,

Have you ensured the SMTP authentication setting is enabled?

Kindest Regards,
Scott M
n/a Points
2015-04-21 2:04 am

Hi Scott

Thanks a lot my friend, but where can i find SMTP Auth.?? did you mean SMTP Authen. in mail server configuration or in pc cliean

Best Regards

Joseph dRego

16,204 Points
2015-04-21 2:11 pm
Hello Joseph,

Thank you for your question. The "SMPT requires authentication" setting i covered in our Outlook 2007 setup guide.

Thank you,

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