---
title: Configuring bounced email monitoring
related:
  - https://docs.kentico.com/13/on-line-marketing-features/managing-your-on-line-marketing-features/email-marketing/monitoring-bounced-marketing-emails.md
---

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>
> - [sitemap.md](https://docs.kentico.com/sitemap.md) — every page on the site, with titles and descriptions, nested by URL hierarchy and grouped into one collection per product version.
> - [llms.txt](https://docs.kentico.com/llms.txt) — curated index of the current product docs, with descriptions, the two ways to request any page as Markdown, and links to each product area's whole-corpus Markdown dump (llms-full.txt).

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:

> **Note:** **Hotfix required**
>
> The features described on this page require [hotfix 13.0.80](https://devnet.kentico.com/download/hotfixes) or newer.

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.<br>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.<br>**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.<br>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.<br>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:<br>**Basic (username + password)** – uses [Basic authentication](https://en.wikipedia.org/wiki/Basic_access_authentication). Fill in the _User name_ and _Password_ settings.<br>**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**.<br>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**.<br>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](https://docs.kentico.com/13/configuring-xperience/configuring-smtp-servers/oauth-for-email-servers.md).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
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.

> **Info:** After you enable and configure bounced email monitoring, the system periodically checks the mailbox where the bounced emails are stored. All contained emails are analyzed and the bounce counter of recipients is increased as needed. After a bounced email is processed, it is deleted from the mailbox. This functionality is ensured by the **Check bounced emails** [scheduled task](https://docs.kentico.com/13/configuring-xperience/scheduling-tasks.md), which runs once per hour by default.