To find out whether, depending on your citizenship, country of long-term residence and the duration and reasons for your stay, you need a visa to enter Italy, see the Italian Ministry of Foreign Affairs website at www.esteri.it/visti/index_eng.asp or check with your local Italian Embassy or other diplomatic representative before you travel.
The rules change regularly, so you should check you have the most up to date information for your trip.
It is the delegate’s responsability to investigate the Visa requirements for Italy and apply for a Conference Invitation Letter (to be addressed to [email protected]) if necessary.