#spring-boot

Learn how to send transactional email from Java using HttpClient, OkHttp, and Spring Boot RestClient. Includes retry logic with idempotency keys, batch sending with Semaphore, and webhook signature verification for Spring Boot and Jakarta Servlet.

Learn how to send transactional email from Kotlin using HttpURLConnection, OkHttp, or the Ktor client. Includes retry logic with idempotency keys, coroutine-based batch sending with Semaphore, and webhook verification for Ktor server and Spring Boot.