Can you please share the exact requirement.
Thank You !
- Create an escalation that will change email address of the contact in the ticket to email@example.com and add this email to the list of emails to not notify in administration ==> Workspace ==> Mail Preferences
- Create a hidden field “Notification” that will be set to NO (via escalation) when the customer is X and the subject is Y and make all your notifications to check this field.
FYI, if it’s not an automated email from your customer; do not use the subject as criteria because you will always have some issues with mistakes in the subject.