Bounces are emails which indicate that a campaign could not be delivered to certain contacts.

Bounce types

There are three types of bounces:

  • Soft Bounces
    Emails could not be delivered because of temporary problems, such as:

    • The mail box of the recipient is full.
    • The denoted domain cannot be reached temporarily or the host is unknown.
    • The email address contained syntax errors.
    • Temporary server breakdowns.
  • Hard Bounces
    Emails could not be delivered because of permanent problems, the common reason being a non-existent email address ("contact unknown").

  • Block Bounces
    Emails could not be delivered because they were blocked by spam filters. Reasons for this could be:

    • Content with suspicious words; emails that contain inappropriate words (in the text body, the subject line or the sender field) are usually rejected.
    • The HTML format in the sent email differs significantly from the HTML standard.
    • A recipient activated a spam filter and has put the sender on its personal spam list.
    • The sender is blacklisted, which means that the contact has informed their internet provider that they consider the email received to be spam.
    • Emails are rejected by the recipient’s server firewall (especially company servers).


Email addresses are either active or inactive. After an email address produced a certain number of bounces, the system assigns the status inactive and no further emails are sent to the address as long as it is not changed.

The threshold value for soft bounces can be defined on the Settings tab.

In the Bounce list, inactive email addresses are marked with an X, while those addresses which have been bounced, but not yet deactivated, are marked with a ?.