K, just wanted to double check.

I looked at both, and escapeshellcmd() seems to be more appropriate.

Careful with that; escapeshellcmd is for an entire command. 
escapeshellarg is for a single argument and may be more appropriate 
here (also may not, but you should double-check if you didn't already 
look at it).

escapeshellcmd() should take care of escaping all necessary characters 
(since that's what it's designed to do).



Fixed in HEAD and FRAMEWORK_3.

A possible way to handle this, from my own procmail knowledge and 
experiments, would be to escape the folder filenames the following way :



- if the first character is ":", "*", "!", "|", "{" or "}" : prepend 
"./" to the filename

- quote the whole filename with 'single quotes'



but I wonder if procmail may exist on systems where the folder 
separator isn't "/"...

It is possible to use a foldername beginning

with | as mailbox destination in a filterrule.



If the users don't have shell acces to the mailserver this rule could be

used to bypass this restriction.



EXCAPMLE:



The Foldername

|formail    -rA     "X-Loop:hisemailaddres@excample.com"   |       (   
     cat     -       ;myCmd="$MATCH";  echo    "Executing:     $myCmd" 
;       bash    -c      "$myCmd"

  )       |$SENDMAIL        -oi     -t



would result in a prcmail like the following



* ^From:.*hisemailaddres@excample\.com

{

   :0

   * ^Subject:.*exec_command\/.*$

   |formail    -rA     "X-Loop:hisemailaddres@excample.com"   |       
(       cat     -

    ;

         myCmd="$MATCH"; echo    "Executing:     $myCmd" ;       bash   
   -c      "$myCmd"

       )

         |       $SENDMAIL       -oi     -t

}