An electronic message processing system includes a classification module for classifying electronic messages, such as e-mails and SMS messages, into one or more categories according to their content. In a preferred embodiment, a text analyzer is used to apply a sequence of one or more rule sets to the content of each message. The rule sets to be applied and their order in the sequence is determined by a hierarchical structure. The use of the hierarchical structure reduces the number of rules which must be applied to a given message. Arranging the rules in sets facilitates administration and maintenance of the rules. A further aspect of the invention involves the instantiation of multiple instances of the text analyzer, one instance for each rule set. This allows an appropriate lexical analysis tool, such as a dictionary in an appropriate language, to be used in conjunction with each rule set.