User signup verification emails that never land in spam

import { SadaSend } from 'sadasend';

const sadasend = new SadaSend({ apiKey: process.env.SADASEND_API_KEY });

export async function sendVerificationOtp(userEmail: string, otpCode: string) {
  const { data, error } = await sadasend.emails.send({
    from: 'Accounts <verify@yourdomain.com>',
    to: userEmail,
    subject: `${otpCode} is your verification code`,
    html: `
      <div style="font-family: sans-serif; max-width: 440px; margin: 0 auto; text-align: center;">
        <h2>Verify your email address</h2>
        <p style="color: #64748b;">Enter this 6-digit code to activate your account:</p>
        <div style="font-size: 32px; font-weight: 700; letter-spacing: 6px; padding: 20px; background: #f1f5f9; border-radius: 8px; margin: 24px 0;">
          ${otpCode}
        </div>
        <p style="color: #94a3b8; font-size: 13px;">Code expires in 10 minutes. If you did not create an account, please ignore this email.</p>
      </div>
    `,
    tags: ['auth', 'verification', 'otp']
  });

  if (error) throw new Error(`Verification dispatch failed: ${error.message}`);
  return data;
}