2010-05-20 02:09 AEST by Glen Starrett - Using Server: Concurrent Versions System (CVSNT) 2.5.03 (Scorpio) Build 3618. 
Haven't checked more recent builds.

When entering a string for "external command" in the email setting applet, the
string gets translated before use so a string like this:

  C:\My_Documents\Downloads\sendmail\sendmail.exe -t

shows up in the trace like this:

10:11:06: S -> CreateProcess(,C:My_DocumentsDownloadssendmailsendmail.exe -t
glen@starretthome.net)

Workaround:  You need to escape the directory separators to enter the external
command string, as follows:

  C:\\My_Documents\\Downloads\\sendmail\\sendmail.exe -t