I have marked this as expired and "Not received".
This letter was automatically registered because the sender marked it as "Mailed" and you as the recepient have not marked it as "Not received".
After letters expire (after 90 days from the sent date), you have another 90 days to mark those letters either by "Mailed" for your outgoing letters or by "Not received" for your incoming letters.
It is important to take an action on each of thise expired letters, otherwise an automatic action will be taken.
You can view your incoming/outgoing expired letters and an explanation of this process in the first page after you log in.