Is it possible to add an Outlook Web Addin function to the context menu? As it was possible with the old VSTO Addins:
I only find some examples with tab ribbons, like:
<!--PrimaryCommandSurface==Main Office Ribbon-->
<ExtensionPoint xsi:type="PrimaryCommandSurface">
<CustomTab id="Contoso.Tab1">
<Group id="Contoso.Tab1.Group1">
<Label resid="Contoso.Tab1.GroupLabel" />
<Icon>
<bt:Image size="16" resid="Contoso.TaskpaneButton.Icon" />
<bt:Image size="32" resid="Contoso.TaskpaneButton.Icon" />
<bt:Image size="80" resid="Contoso.TaskpaneButton.Icon" />
</Icon>
<!--Control. It can be of type "Button" or "Menu" -->
<Control xsi:type="Button" id="Contoso.FunctionButton">
<Label resid="Contoso.FunctionButton.Label" />
Outlook Web Add-ins allow customizing the ribbon by adding commands only. Read more about that in the Add-in commands for Outlook article.
From what I can tell this might be possible. You can find an example here for a different Office app, but I assume that it should hold true for Outlook as well. In Excel a context menu is added with adding the following code to the manifest. Please note that the code below does not include the references (resid's) to urls, long strings and short strings.