Blacklisting googlegroups

[Nikolaos Milas]

Hello,

I am using:
smtpd_recipient_restrictions =
    ...
    check_sender_access hash:/etc/postfix/blacklisted_senders
    ...

to blacklist certain senders in blacklisted_senders file.

I would like to block a certain spam googlegroups mailing list but 
sender is not constant; it's like:

   oursuperclub-members+bncbcg7bjnotikrbewdwpaakgqeabvw...@googlegroups.com

and the <BCG7BJNOTIKRBEWDWPAAKGQEABVW2YA> part is constantly changing.

Which would be the best way to block this?

Please advise.

Thanks,
Nick