Hey Beth, You could add an address attribute to the constituent's home address such as "Acknowledgement" and then filter on that address tab on Step 3. on the Individual Address tab in Donor Acknowledgement letters. Knowledgebase solution BB554666 discusses address attributes, and BB518...

Hi, Ray. To clarify, are you trying to track when organizations' contacts attend an event and then filter mailings on this information? Do you use the Events module? If not, contact attributes may work well, and you will be able to use the Contact Information/Contact Attributes option to only include...