Accessing MAPI-maintained folders in Thunderbird

Hi - I am trying to develop an add-on for Thunderbird, that handles the mails in the folder structure under the mail account - those that are maintained when Thunderbird is synced with the mail account.
I want to find duplicates in order to handle them, before mails are transferred to “Local Folders”. However, it seems that an extension cannot see or access these folders - only those that are under “Local Folders”. Is that true - or how should I access them?
Here is the piece of code that is meant to search the MAPI folders - but doesn’t see anything:

const fullAccount = await browser.accounts.get(account.id);

if (!fullAccount.folders || fullAccount.folders.length === 0) {
console.log(“No folders found in fullAccount.”);
continue;
}
console.log(“Top folders found:”, fullAccount.folders.map(f => f.path));
await scanFolders(fullAccount.folders, duplicateMap, account.name);

Thanks for any answer!
Regards - TorbenRagn

Maybe you should ask here:

Hi C-E
Thank you for advice - and sorry if this was the wrong place for such a question.
I will try your link.
Regards, Torben