Contracts, according to our legislation, have freedom of form. Which means, that contracts are considered to be celebrated as a general rule regardless of the form in which they have been subscribed.
It is erroneously believed that if there is no document, then a contract has not been entered into; on the contrary, previous agreements, either verbally or by mail, are valid. However, there are some contracts that do not follow the general form and there are some formalities that are mandatory by law.
It is important to take into account the role of the notary who will have the possibility to elevate such contract as a public deed if the case requires it.