How to add an entry in Outlook 2010 'New items' ribbon section?

I'm updating an Outlook 2003 plugin to Outlook 2010, and am henceforth dealing with the ribbon.

I already know how to add a new group in the ribbon, via a ribbon.xml file.

But I don't know how to customize an existing ribbon, i.e. add a new entry in the 'New ite开发者_开发问答ms' dropdown button.

I guess one can do it by knowing the right idMso's.

For what it's worth, the project is a .NET 4 VSTO one.

Any idea on this?

Something like this doesn't workn, the GroupMailNew group may be read only, after all:

      <tab idMso="TabMail">
        <group idMso="GroupMailNew">
          <menu idMso="MailNewItemMenu">
            <button id="fooID" label="Foobar"/>
          </menu>
        </group>
      </tab>

I believe you'll find the answer here:

http://msdn.microsoft.com/en-us/library/ee692172.aspx#OfficeOLExtendingUI_NewItemsMenuforJournalModule

This specific example shows how to add a command to the New Items dropdown button.

Just in case the linked page becomes broken, here's the code:

<contextMenus>    
    <contextMenu idMso="MenuMailNewItem">
        <button id="MyMenuMailNewItem"
            label="MenuNewMailItem"
            onAction="OnMyButtonClick"/>
    </contextMenu>  
</contextMenus>