We suggest tracking this type of information using the Mailing Status User Defined Field. Here are the steps for how to mark an account with Do Not Mail status:
  1. In Accounts, click Find an Account.
  2. Search for and click on the name of the User to mark as Do Not Mail. 
  3. Click on the Defined Fields tab under the account header.
  4. Under Tasks, click Show All Fields.
  5. Click on the Mailing Status field.
  6. Mark the checkbox next to the field value selection for Do Not Mail.
  7. Click Save And.

If you do not already have a Mailing Status user defined field ("UDF") set up in your database, you must first create this UDF under the Management tab. The following resource provides instructions for how to set up this user defined field (if necessary): How to track Mailing Status for your Constituents.

Note: Performing these steps (i.e., marking an account with the Do Not Mail status) will NOT automatically remove this account from your Queries/Reports. In order to exclude all accounts marked with this Do Not Mail status, you must use a Clean Mailing List query whenever you are generating documents that will be sent via mail to your constituents. For more on how to set up a Clean Mailing List query, please see the following: How do I create a mailing list that does not include do not mail, bad address, etc. accounts?