Configuring bounced email monitoring

When an email cannot be delivered successfully, an automatic reply informing about the problem is returned (bounced) back to the sender. Tracking bounced emails allows the system to identify email addresses that do not correctly receive marketing emails. Removing invalid addresses from your mailing lists saves bandwidth and improves the accuracy of your subscription statistics, leading to a better delivery rate.

If the number of bounces counted for a recipient reaches a certain limit, the system automatically blocks the corresponding address from receiving any further marketing emails.

To configure bounced email monitoring:

1. Open the Settings application.

2. Navigate to the On-line marketing category.

3. Ensure that the Enable on-line marketing setting is enabled for your site.

4. Select the On-line marketing → Email marketing category of the settings.

5. Enable Monitor bounced emails.

6. Set up the other settings in the Bounced emails and POP3 settings sections:

   Bounced emails
   Bounced email address	The address to which bounced emails are sent when the delivery of a marketing email to a recipient fails. If set, this address is used in the From field of marketing emails.
   Bounced email limit	Sets the amount of bounced emails that can be counted for a recipient before the system blocks them from receiving further marketing emails. This limit is set for all email feeds under the selected site. If you enter 0, the system never blocks recipients automatically.
   Block recipients globally	If enabled, the system uses shared bounce counters for all recipients that have the same email address. This is applied across all sites in the system. Note: This setting does not ensure consistency between the bounce counts of all recipients with a shared address, only that new bounces will be added to all of them. This field is only available when defining global settings, i.e. when the (global) option is selected from the Site drop-down list.
   POP3 settings
   Server name	Sets the the domain name or IP address of the mail server where bounced emails are stored. POP3 is used to check the server and monitor bounced emails. The connection automatically uses the HTTPS protocol if supported by the specified server. The system also automatically chooses the most secure authentication mechanism supported by the server (NTLM, SCRAM, MD5, Plain, etc.).
   Server port	Specifies the number of the port used to connect to the mail server.
   User name	Sets the username for authentication against the mail server.
   Authentication type	Selects the authentication mode used to connect to the mail server. The options are: - **Basic (username \+ password)** – uses [Basic authentication](https://en.wikipedia.org/wiki/Basic_access_authentication). Fill in the *User name* and *Password* settings.- **OAuth 2.0** – uses [OAuth 2.0 token\-based authorization](https://oauth.net/). Fill in the *User name* and select valid *OAuth credentials*.Many mail services are deprecating support of basic authentication, leaving OAuth as the only viable authentication type. A notable example is **Microsoft Exchange Online**, which begins disabling basic authentication after October 1, 2022 (see [Deprecation of Basic authentication in Exchange Online](https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online)).
   Password	Only applies when the Authentication type is set to Basic. Sets the password used together with the User name when connecting to the mail server.
   OAuth credentials	Only applies when the Authentication type is set to OAuth 2.0. Selects the OAuth credentials used for authentication. You can create and manage the credentials in the Email OAuth credentials application. See OAuth for email servers.

7. Click Save.

Some mail servers may be configured to store emails even after they are downloaded, which causes the system to count bounces multiple times (every time the mailbox is checked). You need to adjust the settings of the email server if you experience issues of this type.