It is permissible for the man to talk to a non-Mahram woman, but this might encourage him to commit sins, like looking at her with lust and sexual arousal. Spending long periods of time together could lead to social problems, like making people talking about your relationship or the parents of the girl not being pleased with this. For these reasons, we advise you to correspond with her parents in giving you the chance to get to know her in order to avoid falling into such mistakes.