We would prefer to communicate with intelligent beings in subtle yet artistic manifestations of universal concepts, through media naturally suited to such elegant converse (e.g. crop circles and cattle mutilation). Sadly, certain factors lead us to believe that these efforts have not been entirely successful. We are therefore equipped to receive messages from your primitive Earth electronic mail technology, if your limited intellects can possibly originate concepts of value worth transmission.
If you desire to provide training for our invasion forces, or if you wish to volunteer to be abducted for vivisection experiments, it may be more expedient if you proceed directly to our Mothership or one of our known landing sites, and see what develops. Clan 9, busy as interstellar beavers with conquering planets, abducting midwestern farmers, airlifting randomly selected crafts out of the Bermuda Triangle, and grouting the tiles in our Mothership's shower stalls, will rarely be interested in conducting a coordinated extermination exercise on demand at a certain time or place.
You can recognize members of Clan 9 From Outer Space by the "...C9" suffix appended to our IDs. If we are uniformly sporting snappy neon-yellow battlesuits in imitation of Leader Xris, then we are engaged in a rare moment of cooperation as we enforce our will upon the lesser beings of Earth. Normally, however, we will each be in our individually characteristic colors, doing our loyal best to kill each other as well as any Earthlings in the vicinity (otherwise the challenges in such exercises would be minimal). Death means little when one can Resurrect the Dead (as advertised) through superior extraterrestrial technology. That is, our deaths mean little. Yours we rather enjoy.