Post test mailing refers to the process of sending out a sample of a marketing campaign or advertisement to a select group of recipients after it has been tested. This allows companies to gather feedback and measure the effectiveness of their campaign before launching it on a larger scale. It is a crucial step in the marketing process, as it helps businesses fine-tune their messaging and targeting to ensure maximum impact and return on investment. Post test mailing is often used in direct mail marketing, but can also apply to email, social media, and other forms of advertising. By analyzing the results of a post test mailing, companies can make informed decisions and optimize their marketing strategies for success.