1. A computer implemented method for detecting meaningless lexical units in an electronic message received by a server as to generate an abstract of the electronic message, the method comprising: (i) performing, by the server, a syntax analysis of a most significant part of the electronic message and determining at least one lexical unit as a first potential meaningless lexical unit, the first potential meaningless lexical unit comprising a plurality of control elements, the most significant part of the electronic message having been determined by analyzing a most significant logical block of source code from a plurality of the logical blocks of a source code of the electronic message; (ii) determining, by the server, a numerical control sum of the first potential meaningless lexical unit, the numerical control sum being based on the plurality of control elements having a respective numeric value representative of the first potential meaningless lexical unit; (iii) using the numerical control sum, accessing a lexical unit database located on the server, the lexical unit database containing a plurality of pre-determined meaningless lexical units with their associated pre-determined numerical control sums; (iv) determining, by the server, the first potential meaningless lexical unit is a meaningless lexical unit if the lexical units database includes at least one meaningless lexical unit with the pre-determined numerical control sum matching the numerical control sum of the first potential meaningless lexical unit, the matching comprising checking a measure of a difference between the numerical control sums and determining the numerical control sums as matching if the measure of the difference is within a predefined permissible amplitude of the difference; (v) if the first potential meaningless lexical unit is determined to be the meaningless lexical unit, generating, by the server, the abstract of the electronic message, the abstract not including the at least one meaningless lexical unit.