When a client requests not to receive a certain type of communication you can simply add them to your "Do not call" or "Do not email" list.
Step 1. Edit the client information
Step 2: Locate the contact and select "Edit Contact Preferences" to remove the client from a certain type of communication.
Step 3: Save and then you are all set to go. You will see an orange flag indicating that the contact is set to not receive certain types of communication.