Used stamps exchanges.

I know someone else have talk about this before, I would like to ask what happens when you send a letter to somebody (in Europe) and after more than one month you don´t receive an answer.
Assuming the letter is lost, and it won't count as a sent letter.
How can I free the slot?
The received hasn´t enter in the website more than three weeks ago.
And doesn't answer messages.

Thank you Dave!

Stamps can be registered after 90 days, so it should be OK. You can just get another sending address after 90 days even if they don't register it.

Thank you Marleen! And what happens if arrives, 120 days after sending, the receiver can't register it?

If your envelop wont get registered, it will expire when it travels for 90 days. After this you will be able to request a new address.