Outlook add-in Offline capabilities

Question

Hi, our add-in works on ItemSend event and performs some recipient validation.

I notice that when we go offline, in all clients except new Windows desktop client, the not reachable addin blocks the email upon clicking Send. On mac Send is disabled.

When Offline setting is ON in windows new client the email goes through and will be sent when we come back on-line, but without our addin kicking in in this case.

When Offline is off, outlook will try to reach the addin and the email will be normally blocked as the addin is not reachable at that time.

So, I got a couple of questions around this:

1. Is the Offline toggle the only way to control this behavior in windows client? Is there a manifest/code way to override this or it is always user/admin controlled?
2. Is there a way to "hook into" the send/receive event (that i suppose is happening when getting back on-line) in order to run our add-in validation code?
   The above sounds difficult already, as we will not be in the Compose pane when that happens, so no Item context will be available for the addin, but I need to know if running the same addin or other piece of code that will validate the draft as we need to when coming back on-line is a real option Thanks!

Answer 1

In the context of Outlook add-ins, the behavior regarding the ItemSend event and offline capabilities is influenced by the Outlook client's settings and the add-in's implementation.

1. The Offline toggle is a significant factor in controlling the behavior of the add-in in the Windows client. When the Offline setting is ON, the email can be sent without the add-in's validation, as it does not attempt to reach the add-in. Unfortunately, there is no manifest or code way to override this behavior; it is primarily controlled by user or admin settings.
2. Currently, there is no direct way to hook into the send/receive event that occurs when coming back online to run validation code on drafts. Since the add-in would not be in the Compose pane at that time, the Item context would not be available. Therefore, running the same add-in or another piece of code to validate the draft upon reconnecting is not a supported option.

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References:

• On-send feature for Outlook add-ins
• Handle OnMessageSend and OnAppointmentSend events in your Outlook add-in with Smart Alerts