In email campaigns, how does Braze define a "bounce"?

Braze defines a "bounce" in email campaigns as an email that cannot be delivered to the recipient. This situation occurs when the email server is unable to successfully send the email to the recipient's inbox, which can be due to various reasons. These reasons might include an invalid email address, the recipient's inbox being full, or the email server being temporarily unavailable.

Understanding the concept of a bounce is crucial for managing email campaigns effectively, as high bounce rates can indicate issues with the quality of the email list and may affect the sender's reputation. In contrast, the other options discuss actions taken on an email post-delivery, which do not fit the definition of a bounce. For instance, emails being opened or marked as spam happen after the email has already reached the recipient's server, and forwarding an email indicates successful delivery as well.