The most difficutl item here in Italy is how to access to the AFTN network.
If not readdressed by the flt planning system, the best chance is by using CFMU Eurocontrol sita addresses and including there any address of IFPZ outside country.
(below from AIS Agora forum)
AFTN addresses are build by using apt/fir ICAO code plus:
YAYX Government CAA
YCYX RCC
YDYX Aerodrome Authority
YFYX Aeronautical Fixed Station
YMYX WX Office
YNYX International NOTAM Office
YTYX Telecom Authority
YWYX Military OCC
YXYX Military Ops
ZOZX Oceanic ATCC
ZPZX ARO
ZQZX ARTCC
ZRZX ACC
ZTZX CTL TWR
ZZZX Aircraft inflight
an AFTN Address Indicator is "built" out of the Location Indicator from ICAO Document 7910 and out of the three letter indicator from ICAO Document 8585. In addition a filling letter (usually the "X") has to be added to have an 8 digits Address.
So if you like to get the full information about possible meanings of the last 3 letters check the ICAO Document 8585 where this information comes from.