  We investigate the mass spectrum of the $ss \bar s \bar s$ tetraquark states
within the relativized quark model. By solving the Schr\"{o}dinger-like
equation with the relativized potential, the masses of the $S-$ and $P-$wave
$ss \bar s \bar s$ tetraquarks are obtained. The screening effects are also
taken into account. It is found that the observed resonant structure $X(2239)$
in the $e^+e^- \to K^+K^-$ process by BESIII Collaboration can be assigned as a
$P-$wave $1^{--}$ $ss \bar s \bar s$ tetraquark state. Furthermore, the
radiative transition and strong decay behaviors of this structure are also
estimated, which can provide helpful information for future experimental
searches.
