public class ServicePointManagerX509Helper : IDisposable
{
    private readonly SecurityProtocolType _originalProtocol;

    public ServicePointManagerX509Helper()
    {
        _originalProtocol = ServicePointManager.SecurityProtocol;
        ServicePointManager.ServerCertificateValidationCallback += TrustingCallBack;
    }

    public void Dispose()
    {
        ServicePointManager.SecurityProtocol = _originalProtocol;
        ServicePointManager.ServerCertificateValidationCallback -= TrustingCallBack;
    }

    private bool TrustingCallBack(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
    {
        // The logic for acceptance of your certificates here
        return true;
    }
}