Activation codes are single use and are only valid for a certain period of time. After this, they expire and can no longer be used.
Codes are created when a sender sends a document and Dotpost does not recognise the recipient.
When the activation code expires any associated documents also expire.
Dotpost cannot issue new codes.
If your code has expired, it can no longer be used. The next time your sender sends a document to you, you will receive a new activation code.
You can then create a Dotpost account or add the activation code to your existing account to receive future documents from the sender.