// components/forms/ContactSeller.js
  const handleSubmit = async () => {
    if (auth.user === null && auth.token === "") {
      navigate("/login", {
        state: `/ad/${ad.slug}`,
      });
    }
    setLoading(true);
    try {
      // console.log(name, email, message, phone);
      const { data } = await axios.post("/contact-seller", {
        name,
        email,
        message,
        phone,
        adId: ad._id,
      });
      if (data?.error) {
        toast.error(data.error);
        setLoading(false);
      } else {
        toast.success("Thank you for your enquiry");
        setLoading(false);
      }
    } catch (err) {
      console.log(err);
      setLoading(false);
      toast.error("Something went wrong. Try again.");
    }
  };

Create route and controller function to send email

// routes/ad
router.post("/contact-seller", ad.contactSeller);

// controllers/ad
export const contactSeller = async (req, res) => {
  try {
    const { name, email, message, phone, adId } = req.body;

    const user = await User.findOneAndUpdate(
      { email },
      {
        $addToSet: { enquiredProperties: adId },
      }
    );

    const ad = await Ad.findById(adId).populate("postedBy", "email");

    if (!user) {
      res.json({ error: "Could not find user with that email" });
    } else {
      // send email
      config.AWSSES.sendEmail(
        emailTemplate(
          ad.postedBy.email,
          `
        <p>You have received a new customer enquiry.</p>
        
        <h4>Customer details</h4>
        <p>Name: ${name}</p>
        <p>Email ${email}</p>
        <p>Phone: ${phone}</p>
        <p>Message: ${message}</p>
        <p>Enquiried property:</p>
        <a href="${config.APP_NAME}/ad/${ad.slug}">${ad?.type} in ${ad?.address} for ${ad?.action} $${ad?.price}</a>
    `,
          email,
          "New enquiry received"
        ),
        (err, data) => {
          if (err) {
            return res.json({ error: "Provide a valid email address" });
          } else {
            return res.json({ success: "Check email to access your account" });
          }
        }
      );
    }
  } catch (err) {
    console.log(err);
    res.json({ error: "Something went wrong. Try again." });
  }
};