The aforementioned Net::POP3 is a good module, although I prefer Mail::POP3Client. Here is a sample of its interface:

# taken from perldoc Mail::POP3Client...

       use Mail::POP3Client;
       $pop = new Mail::POP3Client( USER     => "me",
                                    PASSWORD => "mypassword",
                                    HOST     => "pop3.do.main" );
       for( $i = 1; $i <= $pop->Count(); $i++ ) {
         foreach( $pop->Head( $i ) ) {
           /^(From|Subject):\s+/i && print $_, "\n";
         }
       }
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There are ample scripts about the monastery which deal with reading email and writing the file. You would do something like add this line to the above text:

open FILE, "filename" or die "no file! $!";
print FILE $pop -> Body( $i );
close FILE or warn "$!";
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--
Laziness, Impatience, Hubris, and Generosity.