The academia has its own etiquette and if you don’t know it, you run the risk to make stupid mistakes. The following lines are therefore meant for outsiders in order to help them avoiding such formal blunders.
From time to time I receive an email from a student from outside Europe (usually South Asia, but once from the US) who would like to gain a PhD in Europe and often ask whether I could supervise them at one of the Universities I am connected to. Since the pattern has some basic elements which always repeat themselves, I think it is useful to address some of these general points, hoping to help such prospective students.