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.