  We revisit the possibility of producing the observed baryon asymmetry of the
Universe via thermal leptogenesis, where $CP$ violation comes exclusively from
the low-energy phases of the neutrino mixing matrix. We demonstrate the
viability of thermal flavoured leptogenesis across seven orders of magnitude
$\left(10^{6}<T \text{ (GeV)}< 10^{13}\right)$, using modern numerical
machinery, where the lower bound can be reached only if flavour effects are
taken into account and its value depends on the allowed degree of cancellation
between the tree-level and radiative contributions to the light neutrino
masses. At very high scales $\left( T \gg 10^{12} \text{ GeV} \right)$, we
clarify that thermal leptogenesis is sensitive to the low-energy phases, in
contradiction with what is usually claimed in the literature. In particular we
demonstrate that Majorana-phase leptogenesis is in general viable while
Dirac-phase leptogenesis requires some level of fine-tuning.
