private void butDelete_Click(object sender, EventArgs e)
        {
            if (IsNew)
            {
                DialogResult = DialogResult.Cancel;
                return;
            }
            if (EmailAddressCur.EmailAddressNum == PrefC.GetLong(PrefName.EmailDefaultAddressNum))
            {
                MsgBox.Show(this, "Cannot delete the default email address.");
                return;
            }
            if (EmailAddressCur.EmailAddressNum == PrefC.GetLong(PrefName.EmailNotifyAddressNum))
            {
                MsgBox.Show(this, "Cannot delete the notify email address.");
                return;
            }
            Clinic clinic = Clinics.GetFirstOrDefault(x => x.EmailAddressNum == EmailAddressCur.EmailAddressNum);

            if (clinic != null)
            {
                MessageBox.Show(Lan.g(this, "Cannot delete the email address because it is used by clinic") + " " + clinic.Description);
                return;
            }
            if (!MsgBox.Show(this, MsgBoxButtons.OKCancel, "Delete this email address?"))
            {
                return;
            }
            EmailAddresses.Delete(EmailAddressCur.EmailAddressNum);
            DialogResult = DialogResult.OK;          //OK triggers a refresh for the grid.
        }