diff --git a/app/Console/Commands/FetchEmails.php b/app/Console/Commands/FetchEmails.php
index f16a030db..330969781 100644
--- a/app/Console/Commands/FetchEmails.php
+++ b/app/Console/Commands/FetchEmails.php
@@ -428,16 +428,35 @@ public function processMessage($message, $message_id, $mailbox, $mailboxes, $ext
                         $prev_thread_id = '';
 
                         // Customer replied to the email from user
-                        preg_match('/^'.\MailHelper::MESSAGE_ID_PREFIX_REPLY_TO_CUSTOMER."\-(\d+)\-/", $prev_message_id, $m);
-                        if (!empty($m[1])) {
-                            $prev_thread_id = $m[1];
+                        preg_match('/^'.\MailHelper::MESSAGE_ID_PREFIX_REPLY_TO_CUSTOMER."\-(\d+)\-([^@]+)@/", $prev_message_id, $m);
+                        // Simply checking thread_id from message_id was causing an issue when 
+                        // customer was sending a message from FreeScout - the message was 
+                        // connected to the wrong conversation.
+                        if (!empty($m[1]) && !empty($m[2])) {
+                            $message_id_hash = $m[2];
+                            if (strlen($message_id_hash) == 16) {
+                                if ($message_id_hash == \MailHelper::getMessageIdHash($m[1])) {
+                                    $prev_thread_id = $m[1];
+                                }
+                            } else {
+                                // Backward compatibility.
+                                $prev_thread_id = $m[1];
+                            }
                         }
 
                         // Customer replied to the auto reply
                         if (!$prev_thread_id) {
-                            preg_match('/^'.\MailHelper::MESSAGE_ID_PREFIX_AUTO_REPLY."\-(\d+)\-/", $prev_message_id, $m);
-                            if (!empty($m[1])) {
-                                $prev_thread_id = $m[1];
+                            preg_match('/^'.\MailHelper::MESSAGE_ID_PREFIX_AUTO_REPLY."\-(\d+)\-([^@]+)@/", $prev_message_id, $m);
+                            if (!empty($m[1]) && !empty($m[2])) {
+                                $message_id_hash = $m[2];
+                                if (strlen($message_id_hash) == 16) {
+                                    if ($message_id_hash == \MailHelper::getMessageIdHash($m[1])) {
+                                        $prev_thread_id = $m[1];
+                                    }
+                                } else {
+                                    // Backward compatibility.
+                                    $prev_thread_id = $m[1];
+                                }
                             }
                         }
 
diff --git a/app/Jobs/SendAutoReply.php b/app/Jobs/SendAutoReply.php
index a278a316b..3e7f27c7c 100644
--- a/app/Jobs/SendAutoReply.php
+++ b/app/Jobs/SendAutoReply.php
@@ -51,7 +51,7 @@ public function handle()
         $headers['References'] = '<'.$this->thread->message_id.'>';
 
         // Create Message-ID for the auto reply
-        $message_id = \App\Misc\Mail::MESSAGE_ID_PREFIX_AUTO_REPLY.'-'.$this->thread->id.'-'.md5($this->thread->id).'@'.$this->mailbox->getEmailDomain();
+        $message_id = \App\Misc\Mail::MESSAGE_ID_PREFIX_AUTO_REPLY.'-'.$this->thread->id.'-'.\MailHelper::getMessageIdHash($this->thread->id).'@'.$this->mailbox->getEmailDomain();
         $headers['Message-ID'] = $message_id;
 
         $customer_email = $this->conversation->customer_email;
diff --git a/app/Jobs/SendReplyToCustomer.php b/app/Jobs/SendReplyToCustomer.php
index e7a22c79a..60954f2ed 100644
--- a/app/Jobs/SendReplyToCustomer.php
+++ b/app/Jobs/SendReplyToCustomer.php
@@ -173,7 +173,7 @@ public function handle()
             $headers['References'] = '<'.$last_customer_thread->message_id.'>';
         }
 
-        $this->message_id = \App\Misc\Mail::MESSAGE_ID_PREFIX_REPLY_TO_CUSTOMER.'-'.$this->last_thread->id.'-'.md5($this->last_thread->id).'@'.$mailbox->getEmailDomain();
+        $this->message_id = \App\Misc\Mail::MESSAGE_ID_PREFIX_REPLY_TO_CUSTOMER.'-'.$this->last_thread->id.'-'.\MailHelper::getMessageIdHash($this->last_thread->id).'@'.$mailbox->getEmailDomain();
         $headers['Message-ID'] = $this->message_id;
 
         $this->customer_email = $this->conversation->customer_email;
diff --git a/app/Misc/Mail.php b/app/Misc/Mail.php
index cf7c0da14..ac4f21a67 100644
--- a/app/Misc/Mail.php
+++ b/app/Misc/Mail.php
@@ -459,6 +459,11 @@ public static function fetchMessageMarkerValue($body)
         return '';
     }
 
+    public static function getMessageIdHash($thread_id)
+    {
+        return substr(md5($thread_id.config('app.key')), 0, 16);
+    }
+
     /**
      * Detect autoresponder by headers.
      * https://github.com/jpmckinney/multi_mail/wiki/Detecting-autoresponders