title: Why is Logback SMTPAppender only sending 1 email?
body: <p>Here's a snippet containing my Logback <code>SMTPAppender</code>:</p>
  
  <pre><code>&lt;appender name="logManager-smtpAppender" class="ch.qos.logback.classic.net.SMTPAppender"&gt;
      &lt;filter class="ch.qos.logback.classic.filter.LevelFilter"&gt;
          &lt;level&gt;WARN&lt;/level&gt;
          &lt;onMatch&gt;ACCEPT&lt;/onMatch&gt;
          &lt;onMismatch&gt;NEUTRAL&lt;/onMismatch&gt;
      &lt;/filter&gt;
      &lt;filter class="ch.qos.logback.classic.filter.LevelFilter"&gt;
          &lt;level&gt;ERROR&lt;/level&gt;
          &lt;onMatch&gt;ACCEPT&lt;/onMatch&gt;
          &lt;onMismatch&gt;DENY&lt;/onMismatch&gt;
      &lt;/filter&gt;
  
      &lt;asynchronousSending&gt;false&lt;/asynchronousSending&gt;
  
      &lt;smtpHost&gt;my.smtp.host&lt;/smtpHost&gt;
      &lt;to&gt;john.smith@example.com&lt;/to&gt;
      &lt;from&gt;no-reply@example.com&lt;/from&gt;
      &lt;username&gt;my_smtp_user&lt;/username&gt;
      &lt;password&gt;my_smtp_password&lt;/password&gt;
      &lt;subject&gt;%logger{20} - %m&lt;/subject&gt;
      &lt;layout class="ch.qos.logback.classic.html.HTMLLayout"/&gt;
      &lt;cyclicBufferTracker class="ch.qos.logback.core.spi.CyclicBufferTracker"&gt;
          &lt;bufferSize&gt;1&lt;/bufferSize&gt;
      &lt;/cyclicBufferTracker&gt;
  &lt;/appender&gt;
  </code></pre>
  
  <p>When the following Java executes:</p>
  
  <pre><code>logger.warn("This is a warning.");
  logger.error("This is an error.");
  </code></pre>
  
  <p>I only get 1 email. By setting <code>bufferSize</code> to 1 I would have expected to get 2 different emails with 1 single log message in each of them. What's going on?</p>