Option to Hide Users Without Email Addresses from Customer and Recipient Selection

Description

In our Zammad environment at Helmholtz-Zentrum Berlin, some users have two separate accounts: a regular user account with an email address and a specially designated administrative account without an email address.
These administrative accounts are required for system administration and must remain active with their existing permissions.

Current Behavior

When creating or editing a ticket, both accounts appear in the customer selection field, often with identical display names.
The administrative accounts also appear in the email recipient fields (To, CC and BCC), even though they have no email address.
This can lead to users accidentally selecting the wrong account or encountering errors when sending emails.
As a temporary improvement, I have already enabled the following setting:
Setting.set('ui_user_organization_selector_with_email', true)
This makes it easier to distinguish accounts by displaying their email addresses, but it does not prevent administrative accounts from appearing in the selection lists.

Requested Feature

I would like to suggest an optional setting in the Zammad administration interface, for example:
“Hide users without an email address from customer and email recipient selection”
When enabled, this setting should:

  • Hide users without an email address from the customer selection field when creating or editing tickets.
  • Exclude these users from the To, CC and BCC recipient suggestions.
  • Keep these accounts active and fully functional for authentication and administrative tasks.
  • Leave the current behavior unchanged when the setting is disabled.

Benefits

This feature would help organizations that use separate administrative accounts or synchronize users through LDAP.
It would reduce incorrect account selections, prevent email-related errors and improve usability without affecting administrative access.
I believe an optional setting would be a useful addition to Zammad, especially for organizations with multiple accounts per user.
There is already a related community discussion about hiding users without email addresses from recipient suggestions:

My request extends this idea to include the customer selection field as well.
I would appreciate your feedback on whether this could be considered for a future Zammad release.

Thank you!