A Bounce refers to a message that was not delivered. Depending on the reason this happened, we can determine if it is a Hard Bounce or a Soft Bounce. Our CRM delivers reports with all the soft and hard bounces in each campaign.
A Hard Bounce is a permanent reason why a message can't be delivered (ex: non-existent address, blocked email address or non-existent domain). We identify these email addresses and exclude them from future campaigns.
A Soft Bounce indicates a temporary reason why a message can't be delivered (ex: full inbox, the recipient's server is unavailable, or the message is too long).
We will retry the delivery of the message multiple times in a period of 3 days. If this was not successful we'll register it as a Soft Bounce in the campaign report. If the email account continues bouncing in future campaigns, we will consider it like a Hard Bounce and will be deleted from your lists.