Hard bounce

A hard bounce is a rejection that will not change if you try again. The most common cause is an address that does not exist: the person left, the mailbox was deleted, or the address was guessed wrongly. Other permanent causes are a domain that no longer accepts mail and a server that has blocked your sending address outright. The receiving server returns a failure code and the message is gone.

Hard bounces matter more than any other delivery error because providers read them as evidence about your list. Legitimate senders write to people they know; a sender producing many hard bounces looks like someone working from a purchased or scraped list. The consequence is not limited to the bounced message. Your domain’s reputation falls, and mail to valid addresses starts to be filtered as well. Hard bounces should therefore be removed from your data immediately and never contacted again, whatever the campaign.

In Seegnals bounces appear as a Bounced tile in the campaign stats; clicking it shows the affected prospects. Verification on import catches most dead addresses before sending, and the bounce shield pauses the campaign when the bounce count crosses the threshold you set.