A hard bounce tells you that your email cannot be delivered to a particular email address.

It signifies that this is not a temporary signal, but a permanent response for that contact.

A hard bounce can be explained by one of three reasons: the email is invalid, the email domain isn’t real, or the email recipient’s server won’t accept emails. And since a hard bounce is permanent, you should treat these contacts as “unmailable.”

It’s best practice to remove hard bounces from your email list. So you should regularly exclude them from emails and delete them from your email list.