VSTO: Forcing Save Dialogue to appear when an addin custom ribbon button is clicked which updates only a Form region

Question

Using VSTO to create an Outlook Addin, with a custom ribbon and a Form Region.

When I click one of the custom buttons, the region is updated. I need the item (MailItem or AppointmentItem) to know it's been modified so a "do you want to save" dialogue pops up.

I see there is a Saved property, but it's readonly (see https://docs.microsoft.com/en-us/office/vba/api/outlook.mailitem.saved ) is there a way to safely trigger it without a hack (e.g. not item.Subject = item.Subject)

Answer 1

If you are using Outlook Object Model, modifying any property will mark the item as dirty. Are you not modifying the item?

BTW, resetting the Subject property might not be safe as it can wipe out the conversation id. You can reset the MessageClass property instead.