New Post: Restore "Anonymous" or "Default" permissions on mailbox folder in Office 365?

Interesting, here's what I've done:

1. Switched "my" account under the Mail control panel to non-Cached mode.
2. Launched MFCMAPI (x86 version)
3. Enabled both of the settings you suggested.
4. Logged on with "my" account which also auto-maps (full access / owner) to the desired account.
5. I see that the desired account is listed and I can open it's information store.
6. I can then navigate to the "Inbox" folder and see the "PR_NT_SECURITY_DESCRIPTOR" property.
7. When I attempt to delete that property, I get another "MAPI_E_NO_ACCESS" error.
8. To try another avenue, I restarted MFCMAPI and loged on with the target account's credentials and repeated the process.  Same result.

Thanks for you assitance on this, I don't want to tie up your time if this is going to be a mess to figure out.