Index: mimemail.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/mimemail/mimemail.module,v
retrieving revision 1.31.2.3
diff -u -p -r1.31.2.3 mimemail.module
--- mimemail.module	14 Apr 2009 23:08:59 -0000	1.31.2.3
+++ mimemail.module	7 Jul 2009 16:05:44 -0000
@@ -222,14 +222,27 @@ function mimemail_mailengine($op, $messa
         $message['address'] = array($message['address']);
       }
       $status = TRUE;
+      if (variable_get('mimemail_envelope_sender', 0) && !ini_get('safe_mode') && isset($message['headers']['Return-Path'])) {
+        $additional_parameters = '-f'. $message['headers']['Return-Path'];
+      }
       foreach ($message['address'] as $a) {
-        $status = mail(
-          $a,
-          $message['subject'],
-          $message['body'],
-          mimemail_rfc_headers($message['headers'])
-        ) && $status;
-
+        if (isset($additional_parameters)) {
+          $status = mail(
+            $a,
+            $message['subject'],
+            $message['body'],
+            mimemail_rfc_headers($message['headers']),
+            $additional_parameters
+          ) && $status;
+        }
+        else {
+          $status = mail(
+            $a,
+            $message['subject'],
+            $message['body'],
+            mimemail_rfc_headers($message['headers'])
+          ) && $status;
+        }
       }
       return $status;
   }
Index: includes/mimemail.admin.inc
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/mimemail/includes/mimemail.admin.inc,v
retrieving revision 1.1.2.2
diff -u -p -r1.1.2.2 mimemail.admin.inc
--- includes/mimemail.admin.inc	14 Apr 2009 23:09:00 -0000	1.1.2.2
+++ includes/mimemail.admin.inc	7 Jul 2009 16:05:44 -0000
@@ -60,6 +60,12 @@ function mimemail_admin_settings() {
     '#collapsible'   => TRUE,
     '#collapsed'     => TRUE,
   );
+  $form['mimemail']['incoming']['mimemail_envelope_sender'] = array(
+    '#type'          => 'checkbox',
+    '#title'         => t('Set the envelope sender address'),
+    '#default_value' => variable_get('mimemail_envelope_sender', 0),
+    '#description'   => t('This option sets the envelope sender address with the <em>-f</em> sendmail option. This option will not be used if the site is running in <em>safe_mode</em>.'),
+  );
   $form['mimemail']['incoming']['mimemail_incoming'] = array(
     '#type'          => 'checkbox',
     '#title'         => t('Process incoming messages posted to this site'),