We have a similar issue. Our company has two domain names, adeptive.com and adeptivesw.com. Customers can send in tickets to either firstname.lastname@example.org and email@example.com. So, depending on which they send in to, we'll end up with a "cc" on every reply for one of the domains.
In addition, there are multiple email addresses that customers can send to that get routed to the same queue, but the email address is used to indicate the type of request. For example, "upgrades@" and "support@" both come into the Support queue, but upgrades@ tickets are auto-tagged to a specific category. But now whenever an agent replies to an upgrade ticket, upgrades@ is automatically cc:ed.
It would be really nice if there was a list of email addresses that we could exclude from ever being cc:ed.