This paper examines how six online multiclass text classification algorithms perform in the domain of email tagging within the TaskTracer system. TaskTracer is a project-oriented user interface for the desktop knowledge worker. TaskTracer attempts to tag all documents, web pages, and email messages with the projects to which they are relevant. In previous work, we deployed an SVM email classifier to tag email messages. However, the SVM is a batch algorithm whose training time scales quadratically with the number of examples. The goal of the study reported in this paper was to select an online learning algorithm to replace this SVM.