Mabuhay is a traditional Filipino greeting. It literally means »Live!« or »May you live long!« (»buhay« is, after all, Filipino for »life«).
But »Mabuhay« also has an implied meaning of »Welcome!« Thus, the Filipino wishes his/her visitors a warm welcome and a long life as well.
»Mabuhay« has the same encompassing benevolence as the Hawaiian's »Aloha!« or the American Southerner's »Howdy!«
The giving of »Mabuhay!« is often accompanied by a courteous bow or a gentle tap on the shoulder of the guest by the host.
Well, I hope this information suffices anyone's inquiry.
Actually, these are just thoughts coming out the top of my head at 12:30 in the wee morning, so don't quote me on this. I'm not an authority, after all. However, I am a Filipino (and proud of it!) so I think what all that I've just said isn't completely without merit.