It could happen that you can't assign a piece of mail for various reasons: you can't pinpoint or confirm the corresponding owner, a member could have canceled their membership, the uploaded mail was delivered by mistake to your space, or the recipient is no longer a manager of a mailbox.
Whatever it may be, you may prefer to remove it from PilotoMail.
How to remove an unknown mail
You can find all your pending Mail to be assigned under the tab Unassigned.
You can either leave the mail as a pending assignment until you can confirm the owner of the mail item, or delete it from PilotoMail.
To confirm you are removing the correct piece of mail:
Click the mail ID.
From the mail profile, review the front image.
To delete:
Check the box next to the mail ID of the mail piece or pieces you want to delete.
Click the 🗑 trash icon at the end of the row.