I'm required to retrieve mails from Outlook 365 and then update something (a header, the subject, etc.) in order to avoid having the same mail file twice.

Is there any way to achieve this? UIDL and flags aren't useful for us as we're working with many accounts and flags can be removed by users.

Thanks in advance.

I am sorry to say current version doesn't support this feature, how about MarkAsRead method?