text: 'use strict'
  
  const dotenvOptions = {}
  
  if (process.env.NODE_ENV === 'production') {
    // path to a different .env file
    dotenvOptions.path = './.env.production'
  }
  
  require('dotenv').config(dotenvOptions)
  
  const PORT = process.env.MAILER_PORT || 3020
  const WHITELIST = `${process.env.MAILER_WHITELIST}`.split(',')
  const TO = process.env.MAILER_TO
  
  // Transport selector
  const NODEMAILER_TRANSPORT = process.env.MAILER_NODEMAILER_TRANSPORT || 'gmail'
  
  // Mailgun
  const MAILGUN_API_KEY = process.env.MAILER_MAILGUN_API_KEY
  const MAILGUN_DOMAIN = process.env.MAILER_MAILGUN_DOMAIN
  
  // Sendinblue
  const SENDINBLUE_API_KEY = process.env.MAILER_SENDINBLUE_API_KEY
  
  // Gmail
  const GMAIL_SENDER = process.env.MAILER_GMAIL_SENDER
  const GMAIL_PASS = process.env.MAILER_GMAIL_PASS
  
  // SMTP
  const SMTP_HOST = process.env.MAILER_SMTP_HOST
  const SMTP_PORT = process.env.MAILER_SMTP_PORT
  const SMTP_USER = process.env.MAILER_SMTP_USER
  const SMTP_PASS = process.env.MAILER_SMTP_PASS
  
  module.exports = {
    PORT,
    WHITELIST,
    TO,
    NODEMAILER_TRANSPORT,
    MAILGUN_API_KEY,
    MAILGUN_DOMAIN,
    SENDINBLUE_API_KEY,
    GMAIL_SENDER,
    GMAIL_PASS,
    SMTP_HOST,
    SMTP_PORT,
    SMTP_USER,
    SMTP_PASS,
  }
  