What are bounces and how to manage them

A bounce (aka bounceback) is the e-mail message you receive if a sent message doesn't reach its destination. A bounce typically indicates that the message has not been delivered. The system takes care of automatically logging and cataloging bounces for you. In certain cases, it also reacts to them by performing actions such as unsubscribing a recipient whose email address generated a Hard Bounce (see definition below).

Here, let's look at how different types of bounces are defined.

Wrong Address (HB)

What's this?

This error is generated when the local part of an email address is incorrect (e.g. saleees@mycompany.com).

To use the correct address, you should not edit the wrong one, as it has become unsubscribed with no possibility to be subscribed again.

How do I manage it?

The contact is unsubscribed at the first error occurence, with no chance to change its status.

To use the contact, you must add it as new. If you edit the wrong contact, it will stay unsubscribed.

Temporary errors (SB, TB, GB)

What's this?

This error may occur when the domain part of an email address is incorrect (e.g. johndoe@outlook.comm).

How do I manage it?

Edit the contact and change its status to subscribed or pending.

Mailbox full (SBMF)

What's this?

This error generates a temporary error. After a number of unsuccessful retries, it will be unsubscribed.

How do I manage it?

You should ignore these errors, as there are no ways to act on it.

Blocked emails (MB, MBKS, MBSD, MBRD)

What's this?

These errors are generated when the contact is blocked and thus unreachable.

How do I manage it?

To have more info on these occurences, you can request a Deliverability consultancy to get more details

Other / Generic errors (SBDF)

What's this?

This is a delivery error returned from the recipient's (host) domain for an unreachable email address.
These could be temporary recipient server problems or the destination domain does not exist or is written incorrectly.

How do I manage it?

You should ignore these errors, as there are no ways to act on it.