Create/deploy the following “Current User” key to disable the “Url/Email Popup'” from the Citrix Receiver:

(you can paste the following text in notepad and save it as .reg to create an executable registry file)

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Citrix\Receiver]
“SuppressURLPromptAtLogin”=dword:00000001