Bounce, return email from mail server

What is the content of a Bounce notification message?

The content of a Bounce notification message varies depending on the type of Bounce and the mail server. In general, the message contains information about the recipient, the reason for the bounce, the error code, the IP address of the mail server, etc.

What types of bounce are there?

There are two types of bounce: hard bounce and soft bounce. A hard bounce is definitive and means that the email can never be delivered. Soft Bounce is temporary and means that the email could not be delivered for the moment, but can be retried later.

How does the Bounce Rate affect deliverability?

A high Bounce Rate can have a negative impact on email deliverability. Email providers may consider emails with a high Bounce Rate as spam and place them in spam folders or block them completely. It is therefore important to maintain a low bounce rate to improve email deliverability.

Examples

Example of a Bounce message. The subject of the return mail is: “Undelivered Mail Returned to Sender” and the content begins as follows: “This is the mail system at host m-frontend.domaine.com. I am sorry to inform you that your message could not be delivered to one or more recipients. It is attached below (…)”.

Applications

Recognising a bounce is very simple, because it is very often sent by postmaster, or [null] and contains a subject and content that are easily identifiable. On the other hand, it is extremely complex to know whether or not the bounce originates from spam. By default, ALTOSPAM detects whether the bounce is spam and blocks it. However, the administrator has the option of letting all bounces through or blocking them all.

Additional information

• Définition du Bounce selon SearchExchange