code: func (email *Email) SetEmailConfig(host string, port int, username string, password string, from string, to []string) {
  	email.rw.Lock()
  	defer email.rw.Unlock()
  
  	email.host = host
  	email.port = port
  	email.username = username
  	email.password = password
  	email.from = from
  	email.to = to
  	email.formatter = email.formatFunc(email)
  }
docs: // SetEmailConfig allows updating of the email config in flight and is thread safe.