diff --git a/htdocs/core/class/html.formmail.class.php b/htdocs/core/class/html.formmail.class.php
index 9b9bb32865e..38987b36185 100644
--- a/htdocs/core/class/html.formmail.class.php
+++ b/htdocs/core/class/html.formmail.class.php
@@ -908,7 +908,6 @@ class FormMail extends Form
 					$defaultmessage=preg_replace("/^(<br>)+/","",$defaultmessage);
 					$defaultmessage=preg_replace("/^\n+/","",$defaultmessage);
 				}
-
 				$out.= '<tr>';
 				$out.= '<td valign="top">'.$langs->trans("MailText").'</td>';
 				$out.= '<td>';
diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 7a70608f303..05024437a63 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -5733,6 +5733,8 @@ function make_substitutions($text, $substitutionarray, $outputlangs=null)
 	// Make substitition for array $substitutionarray
 	foreach ($substitutionarray as $key => $value)
 	{
+		if (! isset($value)) continue;	// If value is null, it same than not having substitution key at all into array, we do not replace.
+
 		if ($key == '__SIGNATURE__' && (! empty($conf->global->MAIN_MAIL_DO_NOT_USE_SIGN))) $value='';		// Protection
 		if ($key == '__USER_SIGNATURE__' && (! empty($conf->global->MAIN_MAIL_DO_NOT_USE_SIGN))) $value='';	// Protection