Email bounce means an email has returned to the sender and can not be delivered to the inbox. We recognize two types of email bounces:

It's a one-time occurrence and/or temporary delivery issue. It means that the message was recognized by the mail server but was prevented from reaching the inbox. The reasons for that may be:

- the mailbox/server was temporarily unavailable,

- the mailbox was full,

- the message too large (e.g. attachment size limit),

- random occurrence.

The status code for soft bounce always starts with 4xx (example below):

Contacts with soft bounce are eligible to receive an email from you in the future. In all mentioned cases proper action can be taken to deliver such emails without issues. Random occurrence means the bounce reason was unidentified, and a campaign retry is a valid option.

Hard bounce refers to an undeliverable email/permanent delivery issue. The reasons for that are:

- Invalid email address or does not exist anymore,

- Email address blocked (by the server, for security reasons or spam filters),

- Domain name not recognized/non-existent.

The status code for hard bounce always starts with 5xx (example below):

Invalid contacts should be removed or modified. An email address blocked means that the email was not delivered due to the security policies or spam detection. In both scenarios, please follow the best delivery practices to mitigate the risk of such incidents in the future.

Mentioned events will be recorded and easily accessible in Email logs (screenshot below):

The "Bounce type" section will provide you with information about the type and reason/error message (click on a grayed description to expand it).