code: func New(host string, auth smtp.Auth) *MailYak {
  	return &MailYak{
  		headers:        map[string]string{},
  		host:           host,
  		auth:           auth,
  		trimRegex:      regexp.MustCompile("\r?\n"),
  		writeBccHeader: false,
  		date:           time.Now().Format(time.RFC1123Z),
  	}
  }
docs: // New returns an instance of MailYak using host as the SMTP server, and
  // authenticating with auth where required.
  //
  // host must include the port number (i.e. "smtp.itsallbroken.com:25")
  //
  // 		mail := mailyak.New("smtp.itsallbroken.com:25", smtp.PlainAuth(
  // 			"",
  // 			"username",
  // 			"password",
  // 			"stmp.itsallbroken.com",
  //		))
  //