Ferroelectric electron emission (FEE) is an attractive and prospective application of ferroelectric thin film and bulk materials. Although extensive studies have shown that the emission is connected to a change of the ferroelectric polarization, the exact underlying emission process remained unclear to date. Here, FEE from ferroelectric relaxor [Pb(Mg1/3Nb2/3)O3]0.71[PbTiO3]0.29 (PMN-PT) single crystals was investigated by quantifying the amount of emitted electrons as a function of amplitude, pulse repetition rate, and pulse duration of the excitation voltage, hence clarifying the time-resolved emission process. It is demonstrated that FEE from PMN-PT can be described in the framework of a random field model, with the measured electron flux correlating with the amount of reversed polarization. Furthermore, our time-dependent analysis gives insight into the polarization switching and screening processes within PMN-PT. This allows us to draw general conclusions on the future applications of FEE.