The Do Not flags are use for reporting purposes only and do not have any functionality tied to them with regards to filtering the record and removing them from individual group distribution lists.
If you want the Do Not flags to affect how you send Composer emails, you must launch Composer from a query and use the query to exclude these individuals from a Composer message or manually exclude them if you use the Included Groups option to select the email recipients.
If you want to exclude someone from being included in a group distribution list, you would need to either:
- clear their Email 1 field
- update their Preferred Communication Method to “Paper Mail” on the Communication tab of their person record