[logback-user] SMTPAppender mail not sent (logback 1.0.0, JDK 1.5)

I've found the source of the SMTPAppender issues. It with the ThreadPoolExecutor defined in the ContextBase class // 0 idle threads, 2 maximum threads, no idle waiting ExecutorService executorService = new ThreadPoolExecutor(0, 2, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>()); If you increase the first parameter (which is the initial pool size) from 0 to 2, then it works as expected in both JRE 1.5 and 1.6. -dave