We consider the evolution of two-time correlations in the quantum XXZ spin-chain in contact with an environment causing dephasing. Extending quasi-exact time-dependent matrix product state techniques to consider the dynamics of two-time correlations within dissipative systems, we uncover the full quantum behavior for these correlations along all spin directions. Together with insights from adiabatic elimination and kinetic Monte Carlo, we identify three dynamical regimes. For initial times, their evolution is dominated by the system unitary dynamics and depends on the initial state and the Hamiltonian parameters. For weak spin-spin interaction anisotropy, after this initial dynamical regime, two-time correlations enter an algebraic scaling regime signaling the breakdown of time-translation invariance and the emergence of aging. For stronger interaction anisotropy, these correlations first go through a stretched exponential regime before entering the algebraic one. Such complex relaxation arises due to the competition between the proliferation dynamics of energetically costly excitations and their motion. As a result, dissipative heating dynamics of spin systems can be used to probe the entire spectrum of the underlying Hamiltonian.Two-time correlations are powerful tools to capture the fundamental dynamical features of many-body systems both in and away from equilibrium. These correlation functions are of the form B(t 2 )A(t 1 ) where A and B are operators, t 1 and t 2 are two different times, and . . . = tr(ρ . . . ) is the average over the density matrix ρ of a given system. Numerous experimental techniques have been developed to probe these correlations measuring the response of many-body systems. A non-exhaustive list includes ARPES [1], neutron scattering [2] or conductivity and magnetization measurements in solids [3], and radiofrequency [4], Raman, Bragg [5] (and references therein) or modulation spectroscopy [6] in cold gases. In equilibrium, these experimental methods provide information on various spectral features such as collective excitations and bound states. Whereas away from equilibrium, these techniques are employed to identify the formation of dynamically induced states in isolated quantum systems subjected to an external parameter change, and to capture, using for example magnetic susceptibility measurements, the aging dynamics of classical spin glasses [7].Theoretically, two-time correlations have been studied in isolated many-body quantum systems (i.e. not in contact with an environment), both in and far from equilibrium. However, for open many-body quantum systems (i.e. in contact with an environment) evaluating out-of-equilibrium two-time correlations has proven extremely challenging. Most works have instead focused on characterizing the non-equilibrium dynamics of open systems by considering the universal scaling behavior of simpler observables or the propagation of single-time correlations [8,9], by using various approximate approaches to evaluate two-time correlations [10][11][12][13][14...