A filtered keyword list is a list of words or phrases that trigger an automated response when a subscriber replies with them to an email. For example, if "take me off your list" or "opt out" are added to a filtered keyword list with an unsubscribe action, any subscriber who replies with those phrases will be automatically unsubscribed from future emails. This can help NTO handle manual unsubscribe requests more efficiently and avoid sending unwanted emails to their customers. References:
https://help.salesforce.com/articleView?id=sf.mc_es_reply_mail_management.htm&type=5https://help.salesforc