--- /dev/null
+--TEST--
+Bug #21098 Handling of empty plain text parts
+--SKIPIF--
+--FILE--
+<?php
+include "Mail/mime.php";
+
+$mime = new Mail_mime();
+$mime->setTxtBody('');
+$mime->setHTMLBody('<html></html>');
+
+$headers1 = $mime->txtHeaders();
+$body = $mime->get();
+$headers2 = $mime->txtHeaders();
+print strpos($headers1, 'text/html') && strpos($headers2, 'text/html') ? 'OK' : 'NOT OK';
+--EXPECT--
+OK