.cindex "Darwin"
.cindex "Cygwin"
.cindex "exim_msgdate"
-Every message handled by Exim is given a &'message id'& which is sixteen
+Every message handled by Exim is given a &'message id'& which is 23
characters long. It is divided into three parts, separated by hyphens, for
example &`16VDhn-000000001bo-D342`&. Each part is a sequence of letters and digits,
normally encoding numbers in base 62. However, in the Darwin operating