Hi ... I work on an Outlook 2016 add-in (C# visual studio 2017 on Windows 10). The add-in do its job perfectly when a new message is created and then sent from the "Write new message" window launched from the Outlook main menu (or toolbar) : the add-in displays its own ribbon with some radiobuttons to configure the message to be sent and that's all.
But when a new message window is created from the Windows contextual menu "Send to" on a file (to be sent as an attachement), the add-in is ignored : the radio buttons, even if they trigger their respective callbacks and so configure the underlying model, let the new message unchanged :-(
The main difference observed under debugger is :
from the outlook menu : the "ThisAddIn" class seems to retrieve a wrapper for the new message window and so the configuration is taken into account when the message is sent :-)
from the Windows contextual menu : only a "GetCustomUI" callback is triggered and so the message is sent unchanged when the "Send" button is clicked :-(
Any help (examples, documentation, howto, ...) appreciated ...
JF