Old thread, but my issue is one layer deeper - the emails I'm targeting are within a folder, not in inbox.
With emails in folders, solution from @VeronicaDeSalvo doesn't seem to work. When I open an email that's in the subfolder, and copy the URL, I can see this general structure:
https://outlook.office.com/mail/mailboxname@companyname.com/[FolderID]/id/[ConversationID]
But pasting that very same URL back into the browser will open the mailbox with the folder, but does not open the email thread. Is there is some type of argument that needs to get added after ConversationID to open up the email conversation?
The only workaround of sorts I found was using this URL structure:
https://outlook.office.com/mail/deeplink/readconv/ConversationID
ConversationID does still need to go through encodeUriComponent function and the replace advised in this thread. I am using a Compose action to build the URL, so my expression looks like this with concat:
concat('https://outlook.office.com/mail/deeplink/readconv/',replace(encodeUriComponent(ConversationID),'_','%2B'))
The problem with this is that it opens just the email, not the mailbox. Kind of like when you double click on an email as a popout. What I'm looking for is to open the mailbox and then display the email/conversation in question.