<p>Experimental features can be enabled in the miscellaneous-settings tab page.</p>
<p><em>Send hard bounce (version 1.1477+)</em></p>
<p>Send a <ahref="https://tools.ietf.org/html/rfc3464">Delivery Status Notification</a> (=hard bounce) via the reply/answer menu.</p>
<p>Hard bounces will mostly be processed automatically because they affect the reputation of the email provider. The bounce address (=<em>Return-Path</em> header) is mostly very specific, so the email server can determine the sending account.</p>