Context : The current generation of X-ray instruments is progressively revealing more and more details about the complex magnetic field topology and the geometry of the accretion flows in highly magnetized accretion powered pulsars .

Aims : We took advantage of the large collecting area and good timing capabilities of the EPIC cameras on-board XMM-Newton \xspace to investigate the accretion geometry onto the magnetized neutron star hosted in the high mass X-ray binary EXO 2030+375 \xspace during the rise of a source Type-I outburst in 2014 .

Methods : We carried out a timing and spectral analysis of the XMM-Newton \xspace observation as function of the neutron star spin phase .
We used a phenomenological spectral continuum model comprising the required fluorescence emission lines .
Two neutral absorption components are present : one covering fully the source and one only partially .
The same analysis was also carried out on two Suzaku \xspace observations of the source performed during outbursts in 2007 and 2012 , to search for possible spectral variations at different luminosities .

Results : The XMM-Newton \xspace data caught the source at an X-ray luminosity of 2 \times 10 ^ { 36 } erg s ^ { -1 } and revealed the presence of a narrow dip-like feature in its pulse profile that was never reported before .
The width of this feature corresponds to about one hundredth of the neutron star spin period .
From the results of the phase-resolved spectral analysis we suggest that this feature can be ascribed to the self-obscuration of the accretion stream passing in front of the observer line of sight .
We inferred from the Suzaku \xspace observation carried out in 2007 that the self-obscuration of the accretion stream might produce a significantly wider feature in the neutron star pulsed profile at higher luminosities ( \gtrsim 2 \times 10 ^ { 37 } erg s ^ { -1 } ) .

Conclusions : This discovery allowed us to derive additional constraints on the physical properties of the accretion flow in this object at relatively small distances from the neutron star surface .
The presence of such a narrow dip-like feature in the pulse profile is so far unique among all known high mass X-ray binaries hosting strongly magnetized neutron stars .