Entourage and and it's successor Outlook use a database to store or access emails. Up to the 2013 version the databases were prone to corruption. Since the 2016 version the problem has become much better. But where there is a database there is a corruption.
Why you should rebuild your Outlook database?
- Outlook crashes or freezes.
- You get an error message when opening Outlook.
- You get an error message when archiving from Mail Archiver.
How to do the rebuild:
- Quit Outlook.
- First you need to locate Outlook in Finder:
- Do a right-mouse click and select "Show contents". Navigate to "Contents/SharedSupport".
- Start "Outlook Profile Manager". Click on the plus button to create a new profile.
- Click the gear icon to make the profile the default profile.
- Restart Outlook and you will have a blank app: You will now need to re-enter all your accounts.
Accessing your original data
Your old emails aren't gone. But you can only access them if you change the profile with the steps above to the old one. You can easily download everything from your IMAP accounts. But you can't do that with your local mailboxes.
You can try to upload those to an IMAP account and then re-download them into the new profile. Anything else won't work because Outlook still doesn't support export/import of MBOX files.
In earlier times the Outlook data folder was in the User folder. In Outlook 2019 the folder has been hidden. As always Find Any File was able to show me where the Outlook folder is located:
What was a full database in earlier versions now seems to be a more of a central pointer to the final location. The email data is not in the database but in single files. The format of the data is not quite eml. If necessary I would be able to access some of the data. But it's not possible to see which email belongs to which mailboxes.