The SED of the lensed z = 6.56 galaxy HCM6A behind the cluster Abell 370 has been analysed .
We find clear indications for the presence of dust in this galaxy , and we estimate the properties of its stellar populations ( SFR , age , etc . ) .
From its estimated luminosity , L \sim ( 1 - 4 ) \times 10 ^ { 11 } L _ { \odot } , this galaxy ranks as a luminous infrared galaxy .
This case is then used to examine the detectability of high-z galaxies with Herschel and ALMA .
It is evident that with the use of strong gravitational lensing SPIRE/Herschel observations could provide very interesting information on z > 5 galaxies .
Strong synergies between ground-based near-IR instruments on 8-10m class telescopes and ELTs , Herschel , the JWST , and ALMA can be expected for the exploration of the first galaxies in the Universe .