Bounce: means when we send 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.
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.
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.
In NetSuite Failed - invalid address is considered as hard bounce and soft bounce:
- Failed - spam
- Failed - delivery failure
- Failed - other