diff --git a/ChangeLog b/ChangeLog
index 5870e55152d2ed03228a978617baa31b45868e46..0b21f1631365c66bb612181d5e8ee6fb6ab3be99 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -21,6 +21,7 @@ English Dolibarr ChangeLog
 - Fix: [ bug #1812 ] SQL Error message while sending emailing with PostgreSQL datatabase
 - Fix: [ bug #1819 ] SQL error when searching for an invoice payment
 - Fix: [ bug #1827 ] Tax reports gives incorrect amounts when using external modules that create lines with special codes
+- Fix: [ bug #1790 ] Sending a test mail from admin page, gives "File already exists" error
 
 ***** ChangeLog for 3.6.2 compared to 3.6.1 *****
 - Fix: fix ErrorBadValueForParamNotAString error message in price customer multiprice.
diff --git a/htdocs/core/class/html.formmail.class.php b/htdocs/core/class/html.formmail.class.php
index 9d80ced54e34678900c1d1abbec2d944228176cd..45e0aec2f659738844b3e35f8dc733e75201b95d 100644
--- a/htdocs/core/class/html.formmail.class.php
+++ b/htdocs/core/class/html.formmail.class.php
@@ -2,6 +2,7 @@
 /* Copyright (C) 2005-2012 Laurent Destailleur  <eldy@users.sourceforge.net>
  * Copyright (C) 2005-2012 Regis Houssin		<regis.houssin@capnetworks.com>
  * Copyright (C) 2010-2011 Juanjo Menent		<jmenent@2byte.es>
+ * Copyright (C) 2015      Marcos García        <marcosgdf@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -500,6 +501,10 @@ class FormMail
         		$out.= "</td></tr>\n";
         	}
 
+	        if ($this->withform == 1 || $this->withform == -1) {
+		        $out .= '<input style="display:none" type="submit" id="sendmail" name="sendmail">';
+	        }
+
         	// Attached files
         	if (! empty($this->withfile))
         	{