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ClickDimensions Bounce Codes and Service Protection

In email marketing ‘bounce’ is the term given to any email that returned an error stating that the email did not make it to the recipient. The terms hard and soft bounce are commonly used and it is generally accepted that a hard bounce is a permanent failure whereas a soft bounce is a failure that could be temporary. Thus, it makes sense to immediately remove all hard bounce email addresses from your mailing lists and monitor the soft bounce addresses and remove them if the soft bounces continue. ClickDimensions does this automatically through a feature we call Service Protection. This feature ensures that our customers receive high deliverability.

Below are all the possible error messages that can be returned from a ClickDimensions email. In terms of how we treat these errors, codes 10, 21 and 30 (highlighted) are what we consider permanent failures or hard bounces. Thus, when these errors are returned we will no longer allow sends to those email addresses. We consider codes 1, 20, 22 through 70 and 100 to be soft bounces and we will send to an email address returning these errors up to 4 times in a 3 month period. Once we have received the 4th Soft Bounce error for an email address we will no longer allow sending to it.

Table: ClickDimensions Bounce Categories (highlighted items are what we consider to be ‘Hard Bounces’)

Code Category Description
1 Undetermined The response text could not be identified.
10 Invalid Recipient The recipient is invalid.
20 Soft Bounce The message soft bounced.
21 DNS Failure The message bounced due to a DNS failure.
22 Mailbox Full The message bounced due to the remote mailbox being over quota.
23 Too Large The message bounced because it was too large for the recipient.
24 Timeout The message timed out.
25 Admin Failure The message was failed by configured policies.
30 Generic Bounce: No RCPT No recipient could be determined for the message.
40 Generic Bounce The message failed for unspecified reasons.
50 Mail Block The message was blocked by the receiver.
51 Spam Block The message was blocked by the receiver as coming from a known spam source. Spam block events do not count towards the ClickDimensions soft bounce limit.
52 Spam Content The message was blocked by the receiver as spam.
53 Prohibited Attachment The message was blocked by the receiver because it contained an attachment.
54 Relay Denied The message was blocked by the receiver because relaying is not allowed.
70 Transient Failure Message transmission has been temporarily delayed.
80 Subscribe The message is a subscribe request.
90 Unsubscribe The message is an unsubscribe request.
100 Challenge-Response The message is a challenge-response probe.

In the screen shot below you can see that the ClickDimensions solution returns the full text of the error message in the Email Event message field.

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  1. Roman November 8, 2017 at 9:42 am - Reply

    In the blog there is a line ‘ 22 through 70 and 100 to be soft bounces’ but before that ‘codes 10, 21 and 30 (highlighted) are what we consider permanent failures or hard bounces’ .
    So is code 30 message is typical only for hard bounces or also for soft?

  2. Renee Beidler July 19, 2018 at 12:05 am - Reply

    Is there a way to identify soft bounces that result in an excluded recipient/blocked status? We send postcards to all members who have known issues. I’m not certain that I will easily be able to pull the correct soft bounce records.

  3. Gregory September 6, 2018 at 9:36 am - Reply


    How “unsubscribes” within excluded emails statistics report should be interpreted if I do not see any unsubscribes record in the form ?
    Thank you.

    • mm
      ClickDimensions Marketing September 10, 2018 at 8:05 am - Reply

      Hi, Gregory! Often we find that the unsubscribe records have been deleted or the Bulk Email Flag on the Contact record is set to “Do Not Allow.” Sometimes these flags are set by custom workflows (and usually it’s a mistake).

  4. Eric September 17, 2018 at 7:07 pm - Reply


    I’m a little confused by this article and hoping someone can help clarify. Invalid recipient is a hard bounce and the email address should be removed. However the text in the Message field for the example above is showing error code 550 which, through some additional research, sounds like it is typically indicates a Spam filter has rejected the message.

    Why does it make sense to treat a spam filter blocking the email as a hard bounce that get’s excluded from future email sends?

    • mm
      ClickDimensions Marketing September 24, 2018 at 2:19 pm - Reply

      Thanks for your question, Eric! Typically, bounce messages that have a SMTP code starting with 5.x.x are hard bounces/permanent issues/invalid recipients. Soft bounces including spam block issues usually start with a SMTP code of 4.x.x.

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