A search for high-mass resonances in the e+e− final state is presented based on 2.5  fb−1 of s√=1.96  TeV pp collision data from the CDF II detector at the Fermilab Tevatron. The largest excess over the standard model prediction is at an e+e− invariant mass of 240  GeV/c2. The probability of observing such an excess arising from fluctuations in the standard model anywhere in the mass range of 150–1000  GeV/c2 is 0.6% (equivalent to 2.5σ). We exclude the standard model coupling Z′ and the Randall-Sundrum graviton for k/MPl=0.1 with masses below 963 and 848  GeV/c2 at the 95% credibility level, respectively.