private void emailTextBox_Leave(object sender, EventArgs e) { emailTextBox.Enabled = false; if (String.Equals(emailTextBox.Text, email) == false) { datachange = true; if (ValidationCheck.CheckEmail(emailTextBox.Text)) { emailExist.Visible = true; button1.Enabled = false; } else { emailExist.Visible = false; button1.Enabled = true; } } }