mail() function is disabled by default with X10Hosting. Apply for an upgrade the the level two. Just go to your account at you X10Hosting account page. NOT CPANEL!
That would be: http://x10hosting.com/login
Down on the left, select option two (intermediate) and write a short piece explaining why you need mail() to work. Then wait a little (maybe a day or two) and if you get accepted, mail() should work fine for you.