An increasing number of people communicate today via electronic 
means such as email or news forums. One of the basic properties of 
the current electronic communication means is the identification 
of the end-points. However, at times it is desirable or even 
critical to hide the identity and/or whereabouts of the end-points 
(e.g., human users) involved.

This paper discusses the goals and desired properties of anonymous
email in general and introduces the design and salient features of
Babel anonymous remailer. Babel allows email users to converse 
electronically while remaining anonymous with respect to each other 
and to other -- even hostile -- parties. A range of attacks and 
corresponding countermeasures is considered. An attempt is made to 
formalize and quantify certain dimensions of anonymity and untraceable 
communication.