What is the Burofax that Messi sent to Barça in demand to leave and what is it for?

Lionel Messi sent a letter to Barcelona known as the Burofax in Spain to announce to the club that she has made a decision to leave Camp Nou.

What's the Burofax?

Burofax is the service offered by the Spanish Postal Service (Correos) for sending documents when necessary to prove that the document was sent and also to prove the contents of that document.

Burofax is often used when the sender needs to prove legally that the receiver has received the document on the given date and which has been its contents. The court will accept the Burofax sender's bill as evidence that the document in question was sent to the given address.

The Burofax can be sent physically or online through Spain's Post website.

Why did he use the Messy Burofax to let Barcelona know he's leaving?

Messi supports a clause in his contract with Barça, which enables him to break the deal with the unilateral club at the end of each season. This means that Messy was able to do so by May 31st.

However, Messi lawyers argue that extending the 2019/20 season due to the coronary pandemic means that even Messie had time to break the deal.

Based on this argument, Messy had to show Barcelona leaving before the season ended.

His lawyers argue that the 2019/20 season ended on August 23rd, the night the final event of the Champions League was played between Bayern Munich and the SPG.

Using the Burofax, Messi is able to testify that he has announced Barcelona on a certain date (which is said to be 20 August) that he is exercising the right to break the contract.

If this case is brought before judges, Messi's lawyers will be able to use the Burofax to testify that Barcelona was notified of the Messy decision on that date, meaning Barcelona cannot argue that it did not accept the letter, or that the letter arrived later and that the Messiah was delayed in his announcement.