Hi,
An item's immutable ID won't change so long as the item stays in the same mailbox. That means that immutable ID will NOT change if the item is moved to a different folder in the mailbox.
Even if it is a shared mailbox, it should be the same as above.
However, the immutable ID changes if:
- The user moves the item to an archive mailbox.
- The user exports the item (to a PST, as an MSG file, etc.) and re-imports it into their mailbox.
More information you can refer to: : Obtain immutable identifiers for Outlook resources - Microsoft Graph | Microsoft Learn
Please feel free to contact me for any updates.