  A disorder-dependent Gaussian variational approach is applied to the
$d$-dimensional ferromagnetic XY model in a random field. The randomness yields
a non extensive contribution to the variational free energy, implying a random
mass term in correlation functions. The Imry-Ma low temperature result,
concerning the existence ($d>4$) or absence ($d < 4$) of long-range order is
obtained in a transparent way. The physical picture which emerges below $d=4$
is that of a marginally stable mixture of domains. We also calculate within
this variational scheme, disorder dependent correlation functions, as well as
the probability distribution of the Imry-Ma domain size.
