A bounce'means that the email was sent to a specific address, but the mail server that received the email for that person has sent it back, saying it could not be delivered. There are quite a few different reasons that might happen, and it can be divided into two main categories.
A soft bounce is an email message that gets as far as the recipient's mail server (it recognizes the address) but is bounced back undelivered before it gets to the intended recipient. A soft bounce might occur because the recipient's mailbox is full, the server is down or swamped with messages, or the message is too large.
Soft bounces can also include things like auto-replies to the email.
Once an email has soft bounced 3 times without any trackable activity it is automatically be converted to a hard bounce.
A hard bounce is an email message that has been returned to the sender and is permanently undeliverable. Causes include invalid addresses (domain name doesn't exist, typos, changed address, etc.) or the email recipient's mail server has blocked the sender's server. Servers can sometimes interpret bounces differently, meaning a soft bounce on one server may be classified as a hard bounce on another.
In NetSuite, Failed - invalid address is considered as hard bounce, while the following are categorized as soft bounce:
- Failed - spam
- Failed - delivery failure
- Failed - other