The author bought 300 emoji domain names from Kazakhstan and built an email service called Mailoji, which allows users to register email addresses with emoji domains. The author initially purchased a single emoji domain name and then expanded to buying more, eventually creating a service that forwards emails from emoji domains to regular email addresses. The service gained popularity on TikTok and Product Hunt, with over 150 emoji email addresses sold in a day. The author's experience with emoji domains and the challenges of building a business around them are shared in the article.