If these constituents are in a query, and you want to mark them all the same way, and you have supervisor rights, you can do a global change (constituent) and change the "requests no email" field (located within the biographical section) to be a checked field. With regard to adding a DNC flag to the record, you can also globally add a solicit code of "Do Not Call" to the records in the query. Hope this helps.
If these constituents are in a query, and you want to mark them all the same way, and you have supervisor rights, you can do a global change (constituent) and change the "requests no email" field (located within the biographical section) to be a checked field. With regard to adding a DNC flag to the record, you can also globally add a solicit code of "Do Not Call" to the records in the query. Hope this helps.