So... as far as I can tell the only way I can implement this is by adding an `X-MOZ-` property to the item. That should ensure the property is saved with local calendars and at least submitted to remote ones. I do wonder about the potential for mischief however, if the sender overwrites that property.
Bug 1707997 Comment 11 Edit History
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So... as far as I can tell the only way I can implement this is by adding an `X-MOZ-` property to the item. That should ensure the property is saved with local calendars and at least submitted to remote ones. I do wonder about the potential for mischief however, if that property is set externally.