diff --git a/htdocs/core/class/CMailFile.class.php b/htdocs/core/class/CMailFile.class.php
index f3e238c7bf3..32b51c8dd21 100644
--- a/htdocs/core/class/CMailFile.class.php
+++ b/htdocs/core/class/CMailFile.class.php
@@ -466,12 +466,12 @@ class CMailFile
 	/**
 	 * Read a file on disk and return encoded content for emails (mode = 'mail')
 	 *
-	 * @param      sourcefile
-	 * @return     <0 if KO, encoded string if OK
+	 * @param	string	$sourcefile		Path to file to encode
+	 * @return 	int					    <0 if KO, encoded string if OK
 	 */
 	function _encode_file($sourcefile)
 	{
-		$newsourcefile=utf8_check($sourcefile)?utf8_decode($sourcefile):$sourcefile;	// is_readable and file_get_contents need ISO filename
+		$newsourcefile=dol_osencode($sourcefile);
 
 		if (is_readable($newsourcefile))
 		{
@@ -481,7 +481,7 @@ class CMailFile
 		}
 		else
 		{
-			$this->error="Error: Can't read file '$sourcefile'";
+			$this->error="Error: Can't read file '".$sourcefile."' into _encode_file";
 			dol_syslog("CMailFile::encode_file: ".$this->error, LOG_ERR);
 			return -1;
 		}
@@ -491,6 +491,8 @@ class CMailFile
 	/**
 	 *  Write content of a SMTP request into a dump file (mode = all)
 	 *  Used for debugging.
+	 *
+	 *  @return	void
 	 */
 	function dump_mail()
 	{