List hygiene

List hygiene is a best practice in order to maintain a high sending reputation, deliver your messages more quickly and keep high deliverability rates.

Sending messages to inboxes that constantly refuse them affects your reputation as a sender in various ways:

When sending a message to a list triggers a high number of bounces, it means that the list is "dirty": it contains old, incorrect, or otherwise unreachable addresses, which simply should not be there. Maintaining your list "clean" is extremely important: it affects your reputation as a sender, and it also affects your ability to properly analyze the overall performance of your campaigns, ensuring that what you are looking at are accurate statistics. It also impacts your total delivery time, since you are (unnecessarily) sending messages that will not be delivered.

With regard to your reputation, consider that Internet Service Providers (ISPs) keep track of your activity as a sender (they identify you in a variety of ways, including your IP address and domain) and monitor the amount of bounces that you produce (email delivery errors). If that amount exceeds certain parameters, action will be taken, varying from blocking your messages for a certain amount of time to reporting you to one or more blacklists. This will lead to even more bounces, and more delivery problems. So, mail delivery errors can negatively impact your short and long term deliverability.

Our system will help you manage bounces, automating much of the "clean up" process. The system is also constantly updated to implement new email marketing best practices, meaning that new algorithms to further automate the management of bounces are introduced regularly.

However, we recommend that you are even more aggressive and regularly review and clean up addresses that have resulted in multiple bounces.

As a rule of thumb, you should unsubscribe addresses that produce more than 3 consecutive bounces of the same type in time period longer than 15 days. For example, if an address produces a "mailbox full" error (a type of soft bounce) 3 times in a row, and 15 or more days have passed between the first and last bounce, that email address should be reviewed and unsubscribed.

Manual bounce management

Under Recipients > Channels > Email > Bounces,you can view details of delivery errors (bounces) that have been recorded by the system. You will be able to filter based on the type of bounce, the group(s) that the addresses belong to (if applicable), and based on contacts data.

At the bottom of the page you will find buttons that allow you to manage the addresses you have found. You can include recipients with a number of bounces higher than...":

• to an existing group, including the "Unsubscribed" group
• to a new group that you can create

Click on "Move" to start the process. This allows you to exclude those addresses from a future mailing.

Automatic bounce management

The system performs automatic bounce management to minimize the chances of negative effect on your reputation. Error messages are parsed automatically and recipients' behaviors are monitored (opens, clicks) to determine whether a recipient should be unsubscribed or not.

The objective is to balance the negative effects of having a "dirty" list with the problem of unsubscribing recipients that should not be unsubscribed (e.g. mailbox temporarily full).

A carefully calibrated system taking into account industry standards will temporarily unsubscribe recipients who, in a given period of time, will return a number of consecutive bounce for the same reason, without having had recent activities. This will help customers automatically follow best practices and avoid to continue sending to email addresses that can not receive communications.

At the end of the temporary unsubscribe the recipient will be automatically re-entered as subscribed. If a further bounce for the same reason is returned, the recipient will be unsubscribed temporarily for a period of time slightly longer.

Subsequently, if the in box of the recipient continues to be unreachable it will be classified as "permanently unsubscribed to further bounces."
Although it is possible at any time to force the re-submitting, it is highly recommended to do so until the reason has been clarified and the motivation for not delivering the message has been resolved. Otherwise the recipient would be unsubscribed from further sending.

Hard bounce

When a Hard Bounce is received (e.g. 550 5.5.1 "Mailbox not found" or "Unknown user"), that recipient is not included in future mailings. This is true after the first HB and leads to better deliverability for the rest of the list. This task is performed automatically.

If recipients that had generated a HB are included in a mailing, a message is not sent and HB is generated automatically, and added to the HB count for that account. The addresses will be unsubscribed permanently after the first hard bounce"

The reason why addresses are not immediately unsubscribed is that this allows the list administrator still find those recipients in the "Subscribed" group and in the list of recipients for a certain message. If the recipient were immediately unsubscribed, details on the error would not be visible.

Soft bounce

The system automatically manages temporary delivery errors (Soft Bounces) that fall in the categories: SB, SBDF (Domain failure) and SBMF (Mailbox full).

Specifically, on a weekly basis, addresses that generated a soft bounce will be analyzed and unsubscribed automatically when:

• they never opened or clicked on a message sent in the previous 6 months
• they generated soft bounces in 100% of the cases, over the previous 6 months (5 to 10 errors)
• the most recent soft bounce occurred within the previous 3 months

Mail block

The system automatically manages bounces due to mail block that fall in the categories: MB, MBKS (Known Spammer), MBSD (Spam Detected), MBRD (Relay Denied).

In this case, the system will automatically unsubscribe all the recipients that have generated over 50% of bounces in the last 10 mailings, and haven't performed any activity (open/click) in any of these messages

Read more hear about all types of Bounces.