[MM3-users] Bounces address spammed

Greetings, I hope everyone is having a good day. We have a highly visible list that is being spammed with join requests from spoofed addresses. When the confirmation email is sent a bounce is received by the list owner. The count is in the 100’s of bounced emails/hour. We noticed they are all coming from one particular domain, this may help if we are able to filter/block the domain. What would be the best way to handle this? Is there a way to handle this granularly at the list level?

Thank you as always for your assistance. Enrique