diff --git a/src/controllers/09-verification-controller.ts b/src/controllers/09-verification-controller.ts
index cc39433..692a5bf 100644
--- a/src/controllers/09-verification-controller.ts
+++ b/src/controllers/09-verification-controller.ts
@@ -3,8 +3,10 @@ import prisma from "../db";
 import nodemailer from "nodemailer";
 import { notFoundError } from "../utils/error";
 import { RequestWithLineUser } from "../interfaces/user";
+import HttpError from "../interfaces/http-error";
+import HttpStatus from "../interfaces/http-status";
 
-type sendEmail = {
+type SendEmail = {
   email: string;
 } & ({ legalPersonNo: string } | { citizenId: string });
 
@@ -13,6 +15,8 @@ type VerificationPayload = {
   otp: string;
 } & ({ legalPersonNo: string } | { citizenId: string });
 
+let emailTransport: ReturnType<(typeof nodemailer)["createTransport"]>;
+
 @Route("/api/v1/verification")
 @Tags("Verification")
 export class verificationController extends Controller {
@@ -23,7 +27,34 @@ export class verificationController extends Controller {
   }
 
   @Post("/send-otp")
-  public async sendOTP(@Body() body: sendEmail) {
+  public async sendOTP(@Body() body: SendEmail) {
+    if (
+      ![
+        process.env.SMTP_HOST,
+        process.env.SMTP_PORT,
+        process.env.SMTP_USER,
+        process.env.SMTP_PASS,
+      ].every(Boolean)
+    ) {
+      throw new HttpError(
+        HttpStatus.PRECONDITION_FAILED,
+        "SMTP not configured",
+        "smtpNotConfigured",
+      );
+    }
+
+    if (!emailTransport) {
+      emailTransport = nodemailer.createTransport({
+        host: process.env.SMTP_HOST!,
+        port: +process.env.SMTP_PORT!,
+        secure: false, // true for port 465, false for other ports
+        auth: {
+          user: process.env.SMTP_USER!,
+          pass: process.env.SMTP_PASS!,
+        },
+      });
+    }
+
     const generateOTP = Math.floor(100000 + Math.random() * 900000).toString();
     const expiresTime = new Date(Date.now() + 5 * 60 * 1000);
 
@@ -48,17 +79,7 @@ export class verificationController extends Controller {
 
     if (!dataCustomerBranch) throw notFoundError("Customer Branch");
 
-    const fromData = nodemailer.createTransport({
-      host: "smtp.gmail.com",
-      port: 587,
-      secure: false, // true for port 465, false for other ports
-      auth: {
-        user: process.env.SMTP_USER,
-        pass: process.env.SMTP_PASS,
-      },
-    });
-
-    await fromData.sendMail({
+    await emailTransport.sendMail({
       from: process.env.SMTP_USER,
       to: body.email,
       subject: "Your OTP Code",