Is it possible to have two sets of categories in Outlook?

Question

Is it possible to have two sets of categories in Outlook? Like one set of categories are languages which will include 5 languages and second set would be product type. I need to assign language category and product type category to each email.

If it is not possible to have two sets of category, I would like to put all categories to one set but would only like call them separately in combo box.

Like.

Outlook.Application application = new Microsoft.Office.Interop.Outlook.Application();
Outlook.Folder folder = application.ActiveExplorer().CurrentFolder as Outlook.Folder;
Outlook.Store store = folder.Store;
Outlook.Categories categories = store.Categories;
foreach (Outlook.Category category in categories)
{
    if (category != null)
    {
        ComboBox1.Items.Add(category.Name);
    }
    else
    {
        MessageBox.Show("There are no categories.");
    }
}

Is it possible to populate above combo box with only language categories? May be by adding where condition.

I know there is way to do it with user defined properties but wondering if I can achieve this using categories.

Thank you.

Answer 1

将第一组的类别（与语言相关）命名为l_English，l_German等，将第二组的类别（与类型相关）命名为t_construction等。

Answer 2

I follow Victor's suggestion and added same prefix to each category sets. Here is what worked for me, if someone looking for exact answer.

foreach (var category in categories
                    .Cast<Outlook.Category>()
                    .Where(c => c.Name.Contains("l_")))
{
     // do something here
}