We are sending out some 50 variants of newsletters everyday to customers and all the images used are stored on AWS infrastructure. Since we pay for every kilobyte stored on AWS, we want to delete the older images that people might not look at anymore. There would be cron job that finds and deletes older images.
But what is the optimal amount of time the images should be retained? A year, two, or five? I couldn't find an article that discusses this and would like to know what is the best practice in the industry.