Global whitelist entry for domain still blocks subdomains

I always thought that a global whitelist entry for a given sender domain would allow any kind of subdomain entry for that domain, too.
But with Proxmox 3.1 - 5695 this is not working.
If you allow hrs.com as an example then mails from info@newsletter.hrs.com are still blocked.
What is the explanation for this behaviour ?

Regards from Germany,
Philipp