The mailing list for listmasters using Sympa

[Christian Drewing <address@concealed>]

Hi there,

I am a mailing list admin in the company I am working for and I want to block a specified sender from the list. The specified user is spamming our list, but it needs to remain open to non-subscribers due to internal reasons. So is there a way to block the spammer? How can I do that, perhaps with an email command? 

Thank you for support!

Best regards
Christian