"Learning Perl" book, Chapter 1 example: open MAIL, "|mail email_address" doesn't work

[Richard E . Adams]

I am working through the exercises in Chapter 1 of Learning Perl, Second 
Edition, O'Reilly publishers.  I am using MacOS X (10.1.5), and Perl, 
v.5.6.0.  An excerpt from one of the author's programs shows the 
following three lines:

open MAIL, "|mail YOUR_ADDRESS_HERE";
print MAIL "bad news: $someone guessed $someguess\n";
close MAIL;
($someone and $someguess have been assigned appropriate values prior to 
the above three lines.)

I suspect the above works fine in a typical UNIX environment, e.g.,

open MAIL, "|mail [EMAIL PROTECTED]";
print MAIL "bad news: $someone guessed $someguess\n";
close MAIL;
How can I get the above to work on my Macintosh?  (I don't get an error 
message, nor do I receive an email.)  Any help would be greatly 
appreciated.

Richard E. Adams
Email: [EMAIL PROTECTED]