main.js

export default {
  async fetch (request, env) {
    if (request.method === 'POST') {
      const token = request.headers.get('authorization').replace('Bearer ', '')

      if (!env.EMAIL_TOKEN || env.EMAIL_TOKEN.length === 0) {
        return new Response('You must set the Authorization Bearer Token.', {
          status: 401
        })
      }

      if (token !== env.EMAIL_TOKEN) {
        return new Response('Unauthorized', { status: 401 })
      }
      const data = await request.text()
      const body = (!data || data.length === 0) ? {} : JSON.parse(data)

      const response = await fetch('https://api.mailchannels.net/tx/v1/send', {
        method: 'POST',
        headers: { 'content-type': 'application/json' },
        body: JSON.stringify({
          personalizations: [{
            to: body.to || []
          }],
          from: {
            name: body.from.name || body.from.email,
            email: body.from.email || ' '
          },
          subject: body.subject || ' ',
          content: (body.text)
            ? [{
                type: 'text/plain',
                value: body.text || ' '
              }]
            : [{
                type: 'text/html',
                value: body.html || ' '
              }]
        })
      })

      const mailchannel = await response.json()

      // Debugging Logs
      console.log(
        JSON.stringify({
          status: response.status,
          message: response.statusText,
          response: mailchannel
        })
      )

      return new Response(
        JSON.stringify({
          status: response.status,
          message: response.statusText,
          response: mailchannel
        }), {
          status: response.status || 400
        }
      )
    } else {
      return new Response(
        JSON.stringify({
          status: 404,
          message: 'POST request only'
        }), {
          status: 404
        }
      )
    }
  }
}