.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
.code
${run{/bin/bash -c "/usr/bin/id >/tmp/id"}{yes}{yes}}
.endd
+Note that &$value$& will not persist beyond the reception of a single message.
.vindex "&$runrc$&"
The return code from the command is put in the variable &$runrc$&, and this