  Efficient particle acceleration can modify the structure of supernova
remnants. In this context we present the results of the combined analysis of
the XMM-Newton EPIC archive observations of SN 1006. We aim at describing the
spatial distribution of the physical and chemical properties of the X-ray
emitting plasma at the shock front. We investigate the contribution of thermal
and non-thermal emission to the X-ray spectrum at the rim of the remnant to
study how the acceleration processes affect the X-ray emitting plasma. We
perform a spatially resolved spectral analysis on a set of regions covering the
whole rim of the shell and we exploit the results of the spectral analysis to
produce a count-rate image of the "pure" thermal emission of SN 1006 in the
0.5-0.8 keV energy band (subtracting the non-thermal contribution). This image
significantly differs from the total image in the same band, specially near the
bright limbs. We find that thermal X-ray emission can be associated with the
ejecta and we study the azimuthal variation of their physical and chemical
properties finding anisotropies in temperature and chemical composition. Thanks
to our thermal image we trace the position of the contact discontinuity over
the whole shell and we compare it with that expected from 3-D MHD models of
SNRs with unmodified shock. We conclude that the shock is modified everywhere
in the rim and that the aspect angle between the interstellar magnetic field
and the line of sight is significantly lower than 90 degrees
