This guide explains how to manage Soft Bounce and Hard Bounce errors that can occur when sending emails, particularly when using the Infomaniak Newsletter.

Hard Bounce

A hard bounce is an email that cannot be delivered for permanent reasons.

• email sent to a non-existent address
• recipient's email domain which is not a valid domain
• recipient's server that does not accept emails
• etc.

Soft Bounce

A soft bounce is an error message indicating that the email was not delivered to its recipient and corresponds to a temporary delivery issue: the email address is valid, and the sender can resend the email.

Several reasons can explain a soft bounce, meaning that the recipient's server is temporarily refusing the email:

• the recipient's inbox is full: due to insufficient storage capacity, the recipient no longer receives messages
• an issue occurs with the recipient's mail server: the server is temporarily unavailable or down, or the user has unintentionally configured filters that prevent the receipt of certain messages
• when the email content, especially its attached files, is too large, the delivery problem occurs during sending.

Unless the recipient has permanently abandoned their inbox without deleting their account, a soft bounce is a temporary problem.

Example of the Infomaniak Newsletter tool after a sending with a good score of 0% “Permanent bounces” and 0.31% “Temporary bounces”:

Also, refer to this other guide.