Is it worth scanning the contract?

Zawieranie umowy skanem

Signing contracts by hand and sending back scans of them is a common practice. But can it be called fully secure? Is a scanned contract reliable for everyone?

It turns out that the integrity of such a document, i.e. its unaltered form after signing, can be very easily compromised. This raises problems in proving the conclusion of a contract in a given form in court. What is the reason for this? Why should you think twice before entering into a scanned contract?