Different bounce and suppression types

Sometimes emails won’t get through to the recipients inbox. Our email marketing system will let you know why an email has bounced.

There are two types of bounce:

  • Hard bounce:  This occurs when an email is sent to an email address that doesn’t exist anymore or has become invalid. This email address will be placed in the suppression list.
  • Soft bounce:  This occurs when delivery has been successful but another reason has caused the mail to bounce – when the mail has been blocked by the inbox’s filter for example.

Learn more about data hygiene and email bounces.


If an email address bounces too many times, it will be suppressed in your account to stop you from sending to it again. This helps the reputation of your sending address, and prevents your server being blocked for spam.

The default setting will suppress a contact after 1 hard bounce, and to remove a contact without suppression after 4 soft bounces.

Bounce and suppression types

Here are the various types of bounces explained:

  • Globally suppressed – Contacts who have complained to us in the past, or are known spam traps
  • Hard bouncers – Contacts whose addresses are permanently unreachable. The address or server they were hosted on no longer exists.
  • Soft bouncers – Contacts whose addresses are temporarily unavailable. The mailbox may be full or their server is having issues accepting mail.
  • ISP Complainers – Contacts who have submitted spam complaints to their ISP.
  • Mail blockers – Contacts who have received messages that their provider does not want to process.
  • Domain suppression – Contacts whose email has been added to your suppression list.
  • Soft bounce – The mail server didn’t accept the message when you sent it, however, it may send if you try later.
  • Soft bounce DNS failure – Unable to define which mail server is configured to accept mail for this email address.
  • Soft bounce mailbox full – The recipient’s mailbox is too full to accept the message.
  • Soft bounce message too large – The recipient’s mail server won’t accept the size of the message.
  • Bounce no email address – A bounce came back, but we cannot define who the bounce was on behalf of. We can identify the recipients based on the content of the message that was returned.
  • General bounce – The server returned the message, but didn’t state why.
  • Mail blocked – Mail server blocked the email, but didn’t state why.
  • Mail blocked known spammer – The mail sever has decided that your message doesn’t satisfy their filtering criteria and thinks it may be spam. The message has been rejected.
  • Mail blocked relay denied – The mail server says that although the recipient’s domain is pointed at it, it won’t currently accept mail for that domain.

Last Update: June 6, 2018  

 Email Marketing, Reporting & Analytics  
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