I believe it's either an address or a pipe to a script. There may be more possibilities, but you don't need them for this purpose.

In your case, you'd want to put the following into your .forward: 

|/home/foo/mail.pl

[download]
where /home/foo/ is replaced, of course, by the path to your script.

In the script, then, you can just read the message from STDIN. Look at the thread in question for more info.

In reply to Re: .forward by btrott
in thread .forward by Anonymous Monk

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