[otrs] Blacklist addresses

Hi, I have a curious problem: we want to prevent that OTRS sends emails to certain addresses. The reason for this is that some of our customers are replying to mails to mailing lists and put the (read-only) mailing list in Cc. They are unable to actually post to the mailing list, but when we reply to their email, OTRS will put the Cc address as Cc in our reply, thus sending it to the whole list ;-( To prevent this from happening in the future, we would like to setup OTRS in a way that it does not send emails to certain addresses (or domains). Is this possible? -- Daniel Seifert