Hard Bounce
A hard bounce signifies a permanent failure in email delivery, indicating that no further attempts will be made to deliver the message. It’s a definitive indication that an alternative method is needed to reach the intended recipient.
Causes of hard bounce
- Invalid Email Addresses: Hard bounces commonly occur when an email address is entered incorrectly or doesn’t exist.
- ISP Rejection: Internet Service Providers can reject emails for various reasons, such as suspected spam, policy violations, or issues on the recipient’s end.
Soft Bounce
A soft bounce is a temporary failure in email delivery, suggesting that while the email couldn’t be delivered at the moment, the server will attempt further deliveries. Patience is often all that is required.
Causes of Soft Bounce
- Temporary Issues: Soft bounces may occur due to temporary problems, such as a full recipient mailbox, hitting limits on either end, or a message being too large to be accepted.
- Out-of-Office and Auto Responders: Notifications related to out-of-office or other auto responders are sometimes considered soft bounces. However, it’s important to note that they function differently than other soft bounces.
- Other Reasons for Soft Bounce: Soft bounces can also occur for various other reasons, and the way clients communicate these errors may not always be straightforward.