Update:  with the latest Storefront releases, most of this functionality can be achieved from the admin console. Use the ‘Configure Trusted Domains’ task in the Authentication selection and fill out the dialog. The only task then required in the web.config file is to set the hideDomainField to be false to enable the drop down (detail from previous post below still applies here).

Original Post:

The Storefront authentication service can be configured such that when a native Receiver or Receiver for Web is performing explicit authentication a drop down list of domains is shown for user selection.

To enable this list, locate the web.config file in the directory for the Storefront authentication service (normally c:\inetpub\wwwroot\Citrix\authentication\web.config). Open the file in a text editor.

Locate the following section of the file:

<explicitBL authenticator=”defaultDelegatedAuthenticator” hideDomainField=”true” … >
<domainSelection default=””>
<clear />

If not enabled already, change the hideDomainField attribute to be “false”

Add the name of the domain you wish to be default (if any) to the domainSelection default attribute.

For each domain you want to be shown in the drop down add a line of the form
<add domain=”mydomain” />
after the <clear/> line.

An example then might be:

<explicitBL authenticator=”defaultDelegatedAuthenticator” hideDomainField=”false” … >
<domainSelection default=”mydomain“>
<clear />
<add domain=”mydomain” />
<add domain=”engineering” />
<add domain=”busdev” />

This will yield the following prompt on RfW

and on Windows Receiver

In multiple server deployments, ensure that any configuration changes you make are propagated to the rest of the server group so that the configurations of other servers are also updated.