Add troubleshooting adding an email section (#53947)

Co-authored-by: Copilot <[email protected]>
Co-authored-by: Sophie <[email protected]>

content/account-and-profile/setting-up-and-managing-your-personal-account-on-github/managing-email-preferences/adding-an-email-address-to-your-github-account.md

@@ -26,7 +26,32 @@ shortTitle: Add an email address
 {% data reusables.user-settings.access_settings %}
 {% data reusables.user-settings.emails %}
 {% data reusables.user-settings.add_and_verify_email %}
-{% data reusables.user-settings.select_primary_email %}
+1. If you'd like to associate the email address with your web-based Git operations, select it from the "Primary email address" dropdown menu.
+
+   ![Screenshot of the "Email" settings page. Under "Primary email address," a dropdown menu, labeled with Octocat's email address, is outlined in orange.](/assets/images/help/settings/email-primary.png)
+
+## Troubleshooting adding an email
+
+If you see an error message when you try to add an email address to your account, you may be experiencing one of the following issues.
+
+### Email already in use
+
+If you see the error message `Error adding EMAIL: email is already in use`, it means the email address is already linked to another {% data variables.product.prodname_dotcom %} account. An email address can only be associated with one {% data variables.product.prodname_dotcom %} account at a time.
+
+To use this email with a different account, follow these steps:
+
+1. Sign in to the account currently linked to the email address and remove it from that account.
+1. If you don’t have access to the account, request a password reset email to recover it. See [AUTOTITLE](/authentication/keeping-your-account-and-data-secure/updating-your-github-access-credentials).
+
+### Email linked to a {% data variables.enterprise.prodname_managed_user %}
+
+If the email address that you are trying to add is provided to you by your organization, you may see the `Error adding EMAIL: email is already in use` error when your organization has created a {% data variables.enterprise.prodname_managed_user %} for you in their {% data variables.enterprise.prodname_emu_enterprise %}.
+
+Reach out to your site administrator or internal IT helpdesk to learn about their deployment of {% data variables.product.prodname_ghe_cloud %} and how to access the account. You may be able to sign into the {% data variables.product.prodname_ghe_cloud %} application via the organization's identity provider (IdP).
+
+If you want to use your email address with a personal account, you must sign in to your {% data variables.enterprise.prodname_managed_user %} and unverify the email in your account settings. The email will remain linked to your {% data variables.enterprise.prodname_managed_user %}, allowing you to access the account through your organization's IdP.
+
+However, some third-party apps or services may not function properly with a {% data variables.enterprise.prodname_managed_user %} that has an unverified email address.
 
 ## Further reading