Using C# desktop Outlook Addin to detect emails user read on Outlook mobile while the desktop addin was closed

Question

I have a C# Outlook Addin and am trying to detect when a user recently read an email while the desktop outlook was not open (for example they could have read it from outlook mobile). Ideally, I would have been able to restrict the inbox folder items to look for all read items with a recent lastModificationTime when the desktop outlook is relaunched, but it turns out this property is not updated when a user reads an email. So if they just read an email from a few days ago, the lastModificationTime would still be a few days ago (as opposed to a few minutes ago). Is there any recommended+performance-sensitive way to check for emails a user recently read while the desktop outlook was closed?

Thank you,

-Alper

Answer 1

Copy of my reply to your question at the MSDN forum @ https://social.msdn.microsoft.com/Forums/en-US/56808e2a-a0e6-4780-990d-e6aae925fa58/detecting-read-emails-from-ews?forum=outlookdev

No, as you have already discovered, read/unread status is not considered part of the email itself and changing does not update the last modified date. This is done to support per-user read/unread state (e.g. for the Public Folders).