Process for the production of a terephthalate polyester from a monomer mixture comprising a diester

A process for the production of a terephthalate polyester, containing a stage a) for preparing an esterification feedstock containing at least one mixing section fed with at least one terephthalic acid feedstock and one diester monomer feedstock, where the ratio of the total number of moles of diol units with respect to the total number of moles of terephthalate units introduced into the mixing section is between 1.0 and 2.0, the mixing section being operated at a temperature between 25° C. and 250° C. and at a pressure greater than or equal to 0.1 MPa, an esterification stage b) to produce at least one reaction effluent and one aqueous effluent, a polycondensation stage c) to obtain at least the terephthalate polyester and an effluent containing at least one diol monomer, and a stage d) of treatment of the diols to obtain a purified diol stream.