MailgunMailer3.js

class MailgunMailer {
  constructor({ subject, recipients }, content) {
    this.data = {
      from: "[email protected]",
      to: this.formatAdresses(recipients),
      subject: subject,
      html: content
    };
  }

  formatAdresses(recipients) {
    return recipients.map(({ email }) => email).join(",");
  }
}