The term "email bounce" refers to an email that has failed to be delivered and resulted in an error message being sent back to our servers.

We differentiate between the two types of bounces: soft bounces and hard bounces.

A soft bounce is a temporary delivery failure. When an email soft bounces, it means that, in most cases, the email address is valid and your email has reached the mail server of the recipient but the mail server rejected it. It means that your email has not been delivered to the inbox of your recipient (or any of their folders, whether it’s in promotions, spam, etc.).

Here are some common reasons why an email address may soft bounce:

The mail server of the recipient is unavailable.
The inbox is full (over quota).
The domain name doesn't exist.
The email is too large.
The email is blocked because of its content.
The email cannot be relayed between mail servers.
The email cannot be relayed because of unknown reasons.
The email is blocked because of your sender or IP reputation.

How does Sendinblue handle soft bounces?

At Sendinblue, we continue to attempt to resend the email over the next 36 hours until the email is delivered. If it still remains undelivered after these attempts, we stop trying to send the email and we mark it as a soft bounce in the campaign report.

A hard bounce is a permanent delivery failure. In case of a hard bounce, it means that the email has been rejected either because:

the email address of the recipient doesn't exist or is invalid.
the mail server of the recipient has blocked the delivery.

How does Sendinblue handle hard bounces?

At Sendinblue, we automatically blocklist email addresses that hard bounced to prevent you from sending them emails in the future. This means that we don’t try to resend the email as the error is permanent and the contact is blocklisted. This allows you to maintain a clean contact list and get the best results for your next email campaigns.

The email is also immediately marked as a hard bounce in the campaign report.

Where can I view why my email bounced?

When an email bounces, mail servers usually provide the error message of the bounce to Sendinblue. This error message helps you identify the delivery error by including:

The time and date when the email bounced.
The mail server that bounced it.
The reason for the bounce and RFC code (usually a 4XX code is used for soft bounces and a 5XX code for hard bounces).

💡 Good to know

Sometimes, mail servers don't provide the reason for the bounce to Sendinblue. In this case, the reason appears as "unavailable".

You can view the error message of a bounce from the details page of the contacts who bounced. To find which contacts bounced, you can segment them using our Email "classed as a soft bounce" or Email "classed as a hard bounce" conditions.

1️⃣ Segment the contacts who bounced

Go to Contacts.
Click + Add a filter.
Select the following condition:

Email > Email classed as "soft bounce"
Choose which emails > Email Name > Is exactly > enter the name of the email campaign that soft bounced.

Email > Email classed as "hard bounce"
Choose which emails > Email Name > Is exactly > enter the name of the email campaign that hard bounced.

2️⃣ Check why the email bounced

From the segmentation results, click a contact to access their details.
From the history, go to the Marketing tab.
Under the Email campaign event of the email campaign that bounced, click Show details ►.
The error message shows next to the Soft bounce or Hard bounce event.

Do I pay for bounced emails?

You only use your credits the first time we try to send the email. You are not charged when we try to resend the soft-bounced email and we never try resending hard-bounced emails.

If my email bounces, do I get a refund?

If our platform encountered a technical issue that caused your emails to soft bounce, you may be entitled to compensation. Contact our support team by creating a ticket so that we can discuss your options. For any other case, you will not be entitled to compensation.

🤔 Have a question?

If you have a question, feel free to contact our support team by creating a ticket from your account. If you don't have an account yet, you can contact us here.