  We study the properties of one-dimensional topological superconductors under
the influence of generic boundary conditions mimicking the coupling with
external environments. We identify a general four-parameters classification of
the boundary effects and show that particle-hole and reflection symmetries can
be broken or preserved by appropriately fixing the boundary parameters. When
the particle-hole symmetry is broken, the topological protection of the edge
modes is lost due to the hybridization with the external degrees of freedom
(quasiparticle poisoning). We assess the robustness of the edge modes in the
various regimes by considering different quantifiers of topological properties.
In particular, we investigate the resilience of the long-distance, edge-to-edge
quantum mutual information and squashed entanglement, measuring the nonlocal
correlations of the Majorana excitations. Besides their relevance for the open
dynamics of topological systems, these results may provide a useful guide to
the appropriate embedding of low-dimensional topological systems on nanodevices
in realistic conditions.
