Why Does Email Bounce, Bounceback, or Error?

In this article we’ll explain why an email can bounce, how to interpret common email bounceback error messages or codes, and steps to take to help solve your email issues.

Sometimes these email issues can be referred to in multiple ways, it’s common to see them mentioned as a email bounceback or bounce-back message. You might also simply see them referred to as a email bounce, or a non-delivery report.

If you’ve already read about what to do if an email is returned? You should already know some basic reasons for why an email bounceback error message or error code could prevent a successful delivery of your message.

Very briefly some of these common reasons would include a user’s inbox being full, an email account not existing, the IP address of the server or your ISP being blacklisted or blocked, the receiving server using Greylisting to defer the first few email attempts, or server sending limits being exceeded.

What is a Bounceback?

A bounce back message occurs in the form of an email that is sent to your account after the failure to deliver a message that you have attempted to send. This message is generated either by your mail server or the mail server that was the destination of your email. Bounce back messages are a method to let you, the email sender, know that something has happened to disrupt the delivery of your email. This method of providing an error is standard on all email servers, but the actual text used in the messages can vary.

Importance of the Bounce Back Message

Providing the bounce back messages for helping to diagnose email issues is of the utmost importance. Bounce back messages can include vital information about the nature of the issue. Often, these messages will provide the information necessary for technical support to verify server issues as well the exact error type being reported by the server.

Snail Mail vs E-Mail

If you were trying to send a letter to your friend via normal postal mail (snail mail), here are the steps that would need to be taken:

  1. You fill out an envelope with your name and address up at the top-left, and your friend’s name and address in the middle.
  2. You place this envelope in a local postal drop-off box, or your own mailbox to be picked up.
  3. Your envelope gets picked up by your local postal worker and taken to the local sorting facility.
  4. Your envelope gets shipped to the remote sorting facility closest to your friend’s address.
  5. Your envelope gets picked up by the remote postal worker and taken to your friend’s house.

An almost identical process is carried out when trying to deliver an email on the Internet:

  1. Your email client fills out your name and email address into the From: header fields, and you enter in your friend’s name and email address into the To: header fields.
  2. You click send in your email client and wait for it to get picked up by the mail server.
  3. Your email gets picked up by the email server set in your outgoing mail server settings.
  4. Your email attempts to deliver from your email server, to your friends remote e-mail server.
  5. Your email gets delivered by your friend’s remote mail server into their email Inbox.

Why Does E-mail Bounceback?

In the postal mail world, if your envelope was undeliverable, you would typically get your envelope returned to you, stamped with “return to sender on it”. This could happen if either your local postal worker or the one on the remote end can’t read your handwriting or the information is invalid.

A similar scenario also plays out in the email world. Mail servers use something called an MTA (Mail Transfer Agent) to handle email deliveries for the server. If you typed in something incorrectly in your friend’s email address, or there is a temporary delivery problem with their mail server, that remote MTA will send a bounceback message to you with a specific email error message or error code explaining why the message couldn’t be delivered at this time.

Soft Bounce

If the friend you’re trying to email has an email Inbox quota that has been exceeded, or their mail server is temporarily unavailable, your mail server will still try to deliver the email to their mail server. You would then receive a soft bounce from that remote server letting you know that the message was unable to be delivered, typically along with a specific reason.

A soft bounce is typically a temporary problem and you receive a bounceback message from the receipient’s mail server alerting you of the issue so that you can try to send your message again at a later date.

Hard Bounce

If you entered in your friend’s e-mail address incorrectly and your mail server attempts to deliver the email to another remote server that doesn’t handle e-mail for your friend. Then you will get back an almost immediate bounceback error.

A hard bounce can sometimes be a permanent problem, as it is essentially the remote mail server telling you that because the user you tried to e-mail doesn’t exist on their server, it’s not going to start working at a later time.

Blacklisted Bounceback Messages

Blacklisting occurs when mail servers are flagged as being sources of spam. This may not necessarily be true, but if you see that your email is being blocked due to the server being blacklisted, then you will need to submit a request to have the server de-listed. To understand more about blacklisting and the action take if this happens, please see Why do Mail Servers get Blacklisted?

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Thoughts on “Why Does Email Bounce, Bounceback, or Error?

  • InmotionHostings mail server is the one blocking emails. I have tried to send relatives URL links to local news stories and “YOUR” server sends it back as possible spam. I have also had emails sent to GMAIL, AOL and Yahoo that refused my mail claiming the Inmotion IP addresses were blacklisted, how do you explain that. I have found entire IP blocks belonging to Inmotion are blacklisted

  • Good morning.

    i have ane issue i send mail to our client in 2 years before 2016 bt yesterday i recoved email undelivered email message in 14/07/2018. y i recived this message after 2 years please help me

    • You will need to check your email logs to determine why you are receiving that email 2 years later. I am unable to diagnose your email usage and activity to determine why you are receiving specific emails.

  • I have an issue where all external emails are going fine except email sent to a particular domain fails and “Delivery is Delayed to these recipient or group” email notice revieced.

  • I was facing the same error on my Zoho Mail Customer Service mailbox account. After reading here the concept of bounce emails, I will try to improve my email content and control to spread my email contact.

  • I can send individual emails no problem but when I blind copy a large number of  them (150 emails addresses) I am getting the following undeliverable message for all of them. 

     System Adminsstraor:

    Your message did not reach some or all of the intended recipients.The following recipient(s) cannot be reached:




  • Hari OM!
    We ‘TDR Times’ are a social group consisting of members from our school alumni and have a mailing address as ‘********@gmail.com’. We send messages to our members every week pertaining to social issues and news in our village, news about our alumni and articles shared by the alumni. Presently our contacts-list has 270 mebers. This has been going on smoothly for nearly six years without any hassles. But now for the past one month lot of our messages from our GMail account do not reach many recipients and are returned by the mail delivery sub-system with the following message. However, our members have replied that they didn’t receive any message from us and that they have also not blocked our account. Pl help us resolve this problem. The error message is as follows:

    From: Mail Delivery Subsystem Date: Wed, Feb 22, 2017 at 10:09 PMSubject: Delivery Status Notification (Failure)To: ********@gmail.com

    Message blocked
    Your message has been blocked by indira.******@gmail.com. See technical details below for more information. LEARN MORE

    The response from the remote server was:
    Message rejected. See https://support.google.com/mail/answer/69585 for more information.

    Final-Recipient: rfc822; indira.******@gmail.com Action: failed Status: 5.0.0 Diagnostic-Code: smtp; Message rejected. See https://support.google.com/mail/answer/69585 for more information. Last-Attempt-Date: Wed, 22 Feb 2017 08:39:38 -0800 (PST)–
    Best Regards,
    TDR Times….

    • This indicates the email is being delivered successfully to the recipient server, but they are rejecting it. Most likely due to a spam rule. Google suggests creating a group contact, then emailing the group as a possible solution. Alternately, you can ask the recipient to review their email/spam settings.

      Thank you,

  • One of our client try to send us email he is keep getting follwoing error


    Betreff: 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 test.com [X.X.X.X]:
       550 Requested action not taken: mailbox unavailable

    any suggestion 

    • Hello Muhammed,

      We can troubleshoot the email issue if you can provide us a domain name. Otherwise, if you want to handle it privately, please contact our live technical support team via chat/email/phone. The best thing to help this issue is to provide the complete mail header for the initial bounce-back email (the email that identified the error).

      If you have any further questions or comments, please let us know.

      Arnel C.

  • Mails to one particular email id gets returned with 550 no such user message.  The text of the email does not get displayed in return message.


    We have another account in inmotion and the same person receives mails from this .net address but not from .org.  We have been raising tickets for the past two days and also getting in touch on chat but solution is yet to come.  Does it so long to fix this issue?




    • Usually the bounceback provides more information. There may even be a link you can follow for more information. It is clear the message is bouncing back but I advise checking the rest of the bounce message for a more specific cause. You can also our bounceback parser.

  • I am receiving some emails but not all of them. They do not show in Cpanel or Outlook. How can I check to see if these have been put on a black list by accident.

    • Hello Curtis,

      You will want to contact our Live Support with the details of a specific email that you did not get (time it was sent, email address it was sent from) so they can check the email logs to see if it was received and how it was dealt with.

      Kindest Regards,
      Scott M

  • i recieve around 8 copies of emails sent to me & the sender gets told it didnt work & is bounced back to them. I need a solution & happy to pay for it as its been going on for ages & nobody seems to be able to assist.

    • Hello Wayne,

      Thank you for contacting us. We are happy to help you troubleshoot these issues, but will need some additional information.

      When the email bounces back, what is the error message? It will actually tell you why it failed in the bounce back message.

      Have you tried our Bounce Back Tool? It can help read the errors in a returned email.

      Is your email account setup as POP, or IMAP?

      Have you reviewed your mail logs for record of the email transactions, or errors? If you are hosted with us, Live Support can help you review the email logs.

      Thank you,

  • No help at all and try to pass the buck and make ME try to figure out why my REPLY to a long standing supplier is returned as SPAM after years of back and forth emails between us. Easier to pass the buck than actually try to help your customers I guess. Guess it is back to gmail or similar as there seem to be MUCH less problems with them. 

    • I get over 200 REAL spams every day in my inbox that are CLEARLY spam but you can’t tell me why my email is returned as spam when 1) it is a REPLY to my suppliers email, 2) I have sent emails back and forth to this same supplier for YEARS …. There was NO reason this should have happened and personally I just think maybe your company is too lazy to figure out why it was returned. Easier to put the “gobbley gook” you have above and make ME find out why YOUR service is screwed up at this time.

    • Hello Kim,

      I’m sorry that you’re frustrated with the spam issue. It’s been estimated that over 80% of ALL email traffic is spam – and we’re talking well over billions of emails. What we have been trying our best to do is provide guidelines that you can use educate yourself and help to stop spam from being sent – even inadvertently. If you want US to look at your email issue, please provide an email that is being blocked as well as your account information so that we can take a look as to the actual cause. We need email specifics such as the full email and your account information. We could not determine if you were a customer based on the information you have provided. If you are a customer, then we can this information and investigate the issue in more depth.

      If you want the email information to remain private, please indicate this in your reply. We have to approve the comment before it shows on the website. We can remove that information. Also, we do not actually develop the spam software. We can however look to see what rules have been set or how the mail is being processed with a little more info. Please let us know and we would happy to look into this further.

      Arnel C.

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