Opt out of ticket closure auto email?

We're thinking about enabling the auto email closing but we're worried that some clients will want to opt out. Is there any way to set some clients to not receive the email? Thanks.

Alerts to Customers are sent to the email address/es defined under the Ticket Recipients tab. In case a customer asks not to receive alerts you should remove their email address from the External Recipients list managed at the Ticket level. The customer email is added automatically to this list when the Ticket is being opened. You can remove it right from there (the new Ticket window), or, you can remove it from the Account's email address/es (not that ideal) so it'll not be taken automatically.

Hope this helps.
Dina