From 0f2254c5ac0452c437a61476fd559549910f2381 Mon Sep 17 00:00:00 2001
From: Jack Krielen <jackkrielen@bluebirdday.nl>
Date: Mon, 30 Dec 2019 12:12:36 +0100
Subject: [PATCH] Fix magento/magento2#6146

---
 library/Zend/Mail/Transport/Sendmail.php | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/library/Zend/Mail/Transport/Sendmail.php b/library/Zend/Mail/Transport/Sendmail.php
index 3c87aa4e8c..e04e9b2a7a 100644
--- a/library/Zend/Mail/Transport/Sendmail.php
+++ b/library/Zend/Mail/Transport/Sendmail.php
@@ -100,7 +100,8 @@ public function _sendMail()
             $this->recipients,
             $this->_mail->getSubject(),
             $this->body,
-            $this->header);
+            $this->header,
+            $this->_getAdditionalParameters());
         restore_error_handler();
 
         if ($this->_errstr !== null || !$result) {
@@ -202,4 +203,17 @@ public function _handleMailErrors($errno, $errstr, $errfile = null, $errline = n
         return true;
     }
 
+    /**
+     * The additional_parameters parameter can be used to pass additional flags as command line options to the program
+     * configured to be used when sending mail, as defined by the sendmail_path configuration setting.
+     * For example, this can be used to set the envelope sender address when using sendmail with the -f sendmail option.
+     *
+     * @return null|string
+     */
+    protected function _getAdditionalParameters() {
+        if (!empty($this->_mail->getReturnPath())) {
+            return '-f ' . $this->_mail->getReturnPath();
+        }
+        return null;
+    }
 }