When email goes wrong: hard bounces and soft bounces.
Just like regular postal mail, an email will be returned to sender if it cannot be delivered. This is called a bounce.
If you are using Machine Labs you won't see the email coming back as we will automatically deal with it for you.
There are two types of bounces:
1. A Soft Bounce
A soft bounce is a temporary failure to delivery email. This could be because the recipient's email box is full, the receiving email server is too busy or because of some technical failure such as a problem with the internet connection or a failed server.
We automatically re-try soft bounces for you several times before giving up. Soft bounces do not appear as a bounce on your email deliverability reports and do not count towards the 1% bounce limit.
2. A Hard Bounce
A hard bounce means that the attempt to deliver the email has permanently failed. This is usually because the recipient has closed their email account.
A hard bounce will not be retried automatically (and you should not retry either).