diff --git a/app/DataMapper/CompanySettings.php b/app/DataMapper/CompanySettings.php
index 0fc9efb9dae4..3ee028fe98f7 100644
--- a/app/DataMapper/CompanySettings.php
+++ b/app/DataMapper/CompanySettings.php
@@ -163,7 +163,7 @@ class CompanySettings extends BaseSettings
     public $require_quote_signature = false;  //@TODO ben to confirm
 
     //email settings
-    public $email_sending_method = 'default'; //enum 'default','gmail' //@implemented
+    public $email_sending_method = 'default'; //enum 'default','gmail','office365' //@implemented
     public $gmail_sending_user_id = '0'; //@implemented
 
     public $reply_to_email = ''; //@implemented
diff --git a/app/Helpers/Mail/Office365MailTransport.php b/app/Helpers/Mail/Office365MailTransport.php
index 22c7c4bef4bc..e043ded32772 100644
--- a/app/Helpers/Mail/Office365MailTransport.php
+++ b/app/Helpers/Mail/Office365MailTransport.php
@@ -12,6 +12,7 @@
 namespace App\Helpers\Mail;
 
 use Illuminate\Mail\Transport\Transport;
+use Illuminate\Support\Str;
 use Swift_Mime_SimpleMessage;
 use Microsoft\Graph\Graph;
 use Microsoft\Graph\Model\UploadSession;
@@ -29,8 +30,9 @@ class Office365MailTransport extends Transport
         $this->beforeSendPerformed($message);
 
         $graph = new Graph();
+        $token = $message->getHeaders()->get('GmailToken')->getValue();
 
-        $graph->setAccessToken($this->getAccessToken());
+        $graph->setAccessToken($token);
 
         // Special treatment if the message has too large attachments
         $messageBody = $this->getBody($message, true);
@@ -163,7 +165,7 @@ class Office365MailTransport extends Transport
             //add attachments if any
             $attachments = [];
             foreach ($message->getChildren() as $attachment) {
-                if ($attachment instanceof \Swift_Mime_SimpleMimeEntity) {
+                if ($attachment instanceof \Swift_Mime_SimpleMimeEntity && $attachment->getContentType() != 'text/plain') {
                     $attachments[] = [
                         "@odata.type" => "#microsoft.graph.fileAttachment",
                         "name" => $attachment->getHeaders()->get('Content-Type')->getParameter('name'),
@@ -285,23 +287,4 @@ class Office365MailTransport extends Transport
         );
     }
 
-    protected function getAccessToken()
-    {
-        $guzzle = new \GuzzleHttp\Client();
-        $url = 'https://login.microsoftonline.com/' . config('ninja.o365.tenant_id') . '/oauth2/v2.0/token';
-        $token = json_decode($guzzle->post($url, [
-            'form_params' => [
-                'client_id' => config('ninja.o365.client_id'),
-                'client_secret' => config('ninja.o365.client_secret'),
-                'scope' => 'https://graph.microsoft.com/.default',
-                'grant_type' => 'client_credentials',
-            ],
-        ])->getBody()->getContents());
-
-        nlog($token);
-
-        nlog($token->access_token);
-
-        return $token->access_token;
-    }
 }
\ No newline at end of file
diff --git a/app/Jobs/Mail/NinjaMailerJob.php b/app/Jobs/Mail/NinjaMailerJob.php
index 80487f24912d..56f27cd8ec5c 100644
--- a/app/Jobs/Mail/NinjaMailerJob.php
+++ b/app/Jobs/Mail/NinjaMailerJob.php
@@ -184,12 +184,33 @@ class NinjaMailerJob implements ShouldQueue
                 $this->mailer = 'gmail';
                 $this->setGmailMailer();
                 break;
+            case 'office365':
+                $this->mailer = 'office365';
+                $this->setOfficeMailer();
+                break;
             default:
                 break;
         }
 
     }
 
+    private function setOfficeMailer()
+    {
+        $sending_user = $this->nmo->settings->gmail_sending_user_id;
+
+        $user = User::find($this->decodePrimaryKey($sending_user));
+        $token = $user->oauth_user_token->access_token;
+
+        nlog("Sending via {$user->name()}");
+
+        $this->nmo
+             ->mailable
+             ->from($user->email, $user->name())
+             ->withSwiftMessage(function ($message) use($token) {
+                $message->getHeaders()->addTextHeader('GmailToken', $token);     
+             });
+    }
+
     private function setGmailMailer()
     {
         if(LaravelGmail::check())
diff --git a/database/migrations/2022_06_17_082627_change_refresh_token_column_size.php b/database/migrations/2022_06_17_082627_change_refresh_token_column_size.php
new file mode 100644
index 000000000000..9926ae6ab2ec
--- /dev/null
+++ b/database/migrations/2022_06_17_082627_change_refresh_token_column_size.php
@@ -0,0 +1,33 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class ChangeRefreshTokenColumnSize extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+
+        Schema::table('users', function (Blueprint $table) {
+            $table->text('oauth_user_refresh_token')->change();
+        });
+
+        
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        //
+    }
+}