diff --git a/htdocs/core/class/CMailFile.class.php b/htdocs/core/class/CMailFile.class.php
index e23b32c5fb7..3c0e979cbed 100644
--- a/htdocs/core/class/CMailFile.class.php
+++ b/htdocs/core/class/CMailFile.class.php
@@ -1,11 +1,12 @@
 <?php
 /**
- * Copyright (C)           Dan Potter
- * Copyright (C)           Eric Seigne
- * Copyright (C) 2000-2005 Rodolphe Quiedeville <rodolphe@quiedeville.org>
- * Copyright (C) 2003      Jean-Louis Bergamo   <jlb@j1b.org>
- * Copyright (C) 2004-2015 Laurent Destailleur  <eldy@users.sourceforge.net>
- * Copyright (C) 2005-2012 Regis Houssin        <regis.houssin@inodbox.com>
+ * Copyright (C)            Dan Potter
+ * Copyright (C)            Eric Seigne
+ * Copyright (C) 2000-2005  Rodolphe Quiedeville    <rodolphe@quiedeville.org>
+ * Copyright (C) 2003       Jean-Louis Bergamo      <jlb@j1b.org>
+ * Copyright (C) 2004-2015  Laurent Destailleur     <eldy@users.sourceforge.net>
+ * Copyright (C) 2005-2012  Regis Houssin           <regis.houssin@inodbox.com>
+ * Copyright (C) 2019       Frédéric France         <frederic.france@netlogic.fr>
  *
  * 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
@@ -1429,7 +1430,7 @@ class CMailFile
 	 * Return a formatted address string for SMTP protocol
 	 *
 	 * @param	string		$address		     Example: 'John Doe <john@doe.com>, Alan Smith <alan@smith.com>' or 'john@doe.com, alan@smith.com'
-	 * @param	int			$format			     0=auto, 1=emails with <>, 2=emails without <>, 3=auto + label between "
+	 * @param	int			$format			     0=auto, 1=emails with <>, 2=emails without <>, 3=auto + label between ", 4 label or email, 5 mailto link
 	 * @param	int			$encode			     0=No encode name, 1=Encode name to RFC2822
 	 * @param   int         $maxnumberofemail    0=No limit. Otherwise, maximum number of emails returned ($address may contains several email separated with ','). Add '...' if there is more.
 	 * @return	string						     If format 0: '<john@doe.com>' or 'John Doe <john@doe.com>' or '=?UTF-8?B?Sm9obiBEb2U=?= <john@doe.com>'
@@ -1437,6 +1438,7 @@ class CMailFile
 	 *										     If format 2: 'john@doe.com'
 	 *										     If format 3: '<john@doe.com>' or '"John Doe" <john@doe.com>' or '"=?UTF-8?B?Sm9obiBEb2U=?=" <john@doe.com>'
 	 *                                           If format 4: 'John Doe' or 'john@doe.com' if no label exists
+     *                                           If format 5: <a href="mailto:john@doe.com">John Doe</a> or <a href="mailto:john@doe.com">john@doe.com</a> if no label exists
 	 */
 	public static function getValidAddress($address, $format, $encode = 0, $maxnumberofemail = 0)
 	{
@@ -1466,6 +1468,10 @@ class CMailFile
 				$i++;
 
 				$newemail='';
+                if ($format == 5) {
+                    $newemail = $name?$name:$email;
+                    $newemail = '<a href="mailto:'.$email.'">'.$newemail.'</a>';
+                }
 				if ($format == 4)
 				{
 					$newemail = $name?$name:$email;