Postmark send mail to multiple users

Question

I want to send email to multiple users in a single request by putting them all in Bcc and in to I put myself that is my second email so that all the users get mail but I got error that Bcc is not with correct format

const broadCastEmail = async (emails) => {
  // Create a Postmark client with your server token
  const client = new postmark.ServerClient(
    "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
  );

  const path = "./public/logo.png";
  const logoAttachment = await createAttachment(path, "Logo_solo.png");
  console.log(emails);

  const emailParams = {
    From: "[email protected]",
    To: "[email protected]", // You can set the primary recipient here
    Bcc: ["[email protected]", "[email protected]"],
    Subject: "Your email subject",
    HtmlBody: "<p>Hello, this is a test email.</p>",
    Attachments: logoAttachment,
  };

  // Send the email
  client
    .sendEmail(emailParams)
    .then((response) => {
      console.log("Email sent successfully");
      console.log(response);
    })
    .catch((error) => {
      console.error("Error sending email:", error);
    });
};