Call down to any Realtor. I believe the place is called Windrush. Weekend and weekly rentals available right on the beach.
Nice place. Not too fancy and the price is right.
When you configured your linux box did you configure it to receive email? If you did, then just setup your email account on it. configure it to not check for email and use it for your sendmail only.
Otherwise, check this list of free smtp servers!
http://www.e-eeasy.com/SMTPServerList.aspx
I would stick with the yahoo servers. You have better luck of them staying up!