MDL-69265 email: Add admin setting for email headers

admin/settings/server.php

@@ -363,8 +363,11 @@
                  new lang_string('onlynoreply', 'admin'));
 $temp->add(new admin_setting_configselect('emailfromvia', new lang_string('emailfromvia', 'admin'),
           new lang_string('configemailfromvia', 'admin'), 1, $choices));
-    $temp->add(new admin_setting_configtext('emailsubjectprefix', new lang_string('emailsubjectprefix', 'admin'),
+
+$temp->add(new admin_setting_configtext('emailsubjectprefix', new lang_string('emailsubjectprefix', 'admin'),
         new lang_string('configemailsubjectprefix', 'admin'), '', PARAM_RAW));
+$temp->add(new admin_setting_configtextarea('emailheaders', new lang_string('emailheaders', 'admin'),
+        new lang_string('configemailheaders', 'admin'), '', PARAM_RAW, '50', '3'));
 
 $ADMIN->add('email', $temp);
 

lang/en/admin.php

@@ -228,6 +228,7 @@
 $string['configemailchangeconfirmation'] = 'Require an email confirmation step when users change their email address in their profile.';
 $string['configemailfromvia'] = 'Add via information in the "From" section of outgoing email. This informs the recipient from where this email came from and also helps combat recipients accidentally replying to no-reply email addresses.';
 $string['configemailsubjectprefix'] = 'Text to be prefixed to the subject line of all outgoing mail.';
+$string['configemailheaders'] = 'Raw email headers to be added verbatum to all outgoing email.';
 $string['configenablecalendarexport'] = 'Enable exporting or subscribing to calendars.';
 $string['configenablecomments'] = 'Enable comments';
 $string['configenablecourserequests'] = 'If enabled, users with the capability to request new courses (moodle/course:request) will have the option to request a course. This capability is not allowed for any of the default roles. It may be applied in the system or category context.';
@@ -516,6 +517,7 @@
 $string['editstrings'] = 'Edit words or phrases';
 $string['emailchangeconfirmation'] = 'Email change confirmation';
 $string['emailfromvia'] = 'Email via information';
+$string['emailheaders'] = 'Email headers';
 $string['emailsubjectprefix'] = 'Email subject prefix text';
 $string['emoticontext'] = 'Text';
 $string['emoticonimagename'] = 'Image name';

lib/moodlelib.php

@@ -6221,6 +6221,15 @@ function email_to_user($user, $from, $subject, $messagetext, $messagehtml = '',
         $mail->addCustomHeader('X-Moodle-Originating-Script: ' . $originheader);
     }
 
+    if (!empty($CFG->emailheaders)) {
+        $headers = array_map('trim', explode("\n", $CFG->emailheaders));
+        foreach ($headers as $header) {
+            if (!empty($header)) {
+                $mail->addCustomHeader($header);
+            }
+        }
+    }
+
     if (!empty($from->priority)) {
         $mail->Priority = $from->priority;
     }

lib/tests/moodlelib_test.php

@@ -3220,6 +3220,32 @@ public function test_generate_email_messageid($wwwroot, $msgids) {
         }
     }
 
+    /**
+     * Test email with custom headers
+     */
+    public function test_send_email_with_custom_header() {
+        global $DB, $CFG;
+        $this->preventResetByRollback();
+        $this->resetAfterTest();
+
+        $touser = $this->getDataGenerator()->create_user();
+        $fromuser = $this->getDataGenerator()->create_user();
+        $fromuser->customheaders = 'X-Custom-Header: foo';
+
+        set_config('allowedemaildomains', 'example.com');
+        set_config('emailheaders', 'X-Fixed-Header: bar');
+
+        $sink = $this->redirectEmails();
+        email_to_user($touser, $fromuser, 'subject', 'message');
+
+        $emails = $sink->get_messages();
+        $this->assertCount(1, $emails);
+        $email = reset($emails);
+        $this->assertContains('X-Custom-Header: foo', $email->header);
+        $this->assertContains("X-Fixed-Header: bar", $email->header);
+        $sink->clear();
+    }
+
     /**
      * A data provider for testing email diversion
      */