diff --git a/app/Helper/MailHelper.php b/app/Helper/MailHelper.php
index b42d83abf..cb16d6f88 100644
--- a/app/Helper/MailHelper.php
+++ b/app/Helper/MailHelper.php
@@ -40,8 +40,9 @@ class MailHelper extends Base
      */
     public function filterSubject($subject)
     {
-        $subject = str_replace('RE: ', '', $subject);
-        $subject = str_replace('FW: ', '', $subject);
+        $subject = str_ireplace('RE: ', '', $subject);
+        $subject = str_ireplace('FW: ', '', $subject);
+        $subject = str_ireplace('Fwd: ', '', $subject);
 
         return $subject;
     }
diff --git a/tests/units/Helper/MailHelperTest.php b/tests/units/Helper/MailHelperTest.php
index e871a57d6..c6f130423 100644
--- a/tests/units/Helper/MailHelperTest.php
+++ b/tests/units/Helper/MailHelperTest.php
@@ -20,6 +20,7 @@ class MailHelperTest extends Base
         $this->assertEquals('Test', $helper->filterSubject('Test'));
         $this->assertEquals('Test', $helper->filterSubject('RE: Test'));
         $this->assertEquals('Test', $helper->filterSubject('FW: Test'));
+        $this->assertEquals('Test', $helper->filterSubject('Fwd: Test'));
     }
 
     public function testGetSenderAddress()