function sendEmails() {
  const sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const data = sheet.getDataRange().getValues();
  
  for (let i = 0; i < data.length; i++) {
    const row = data[i];
    const email = row[0];
    const username = row[1];
    const password = row[2];

    if (email) {
      const subject = "ICPC Minya — Creativa Wi-Fi Credentials";

      const htmlMessage = `
        <p style="font-size: 24px">Dear Participant,</p>

        <p>Welcome to the ICPC Minya session at Creativa Hub!</p>

        <p><b>Here are your personal Wi-Fi credentials:</b></p>
        <ul>
          <li><b>Username:</b> ${username}</li>
          <li><b>Password:</b> ${password}</li>
        </ul>

        <p><b>⚠️ Please note:</b></p>
        <ul>
          <li>Do <b>not</b> share your credentials with anyone.</li>
          <li>Do <b>not</b> use hotspot or share your connection.</li>
          <li>Connect only on the device you’ll be using during the session.</li>
        </ul>

        <p>Best regards,<br>
        <b>ICPC Minya Team</b></p>
      `;

      MailApp.sendEmail({
        to: email,
        subject: subject,
        htmlBody: htmlMessage
      });
    }
  }
}