private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
		if (JOptionPane.OK_OPTION == JOptionPane.showConfirmDialog(null,
				"ȷʵҪɾ˼¼", "ʾ	", JOptionPane.OK_CANCEL_OPTION)) {
			userlist.remove(userList.getSelectedIndex());
			lm.remove(userList.getSelectedIndex());
			User u = userlist.get(0);
			usernameTextField.setText(u.getUsername());
			passwordTextField.setText(u.getPassword());
			for (int i = 0; i < smtpComboBox.getItemCount(); i++) {
				if (u.getSmtpServer().equals(smtpComboBox.getItemAt(i))) {
					smtpComboBox.setSelectedIndex(i);
					break;
				}
			}
			for (int i = 0; i < popComboBox.getItemCount(); i++) {
				if (u.getPopServer().equals(popComboBox.getItemAt(i))) {
					popComboBox.setSelectedIndex(i);
					break;
				}
			}
		}
	}