Sun Java System Messaging Server 6.3 Administration Guide

11.6.3 Literal Character Substitutions, $$, $%, $@

The $, %, and @ characters are normally metacharacters in rewrite rule templates. To perform a literal insertion of such a character, quote it with a dollar character, $. That is, $$ expands to a single dollar sign, $; $% expands to a single percent, % (the percent is not interpreted as a template field separator in this case); and $@ expands to a single at sign, @ (also not interpreted as a field separator).