open(PIPEWRITE, '|./program')
    or die "Can't start pipe: $!";
print PIPEWRITE for @array;
close PIPEWRITE 
    or die "Cant't close pipe: $!";

##</code><code>##

open(PIPEWRITE, '|./program > output');

##</code><code>##

use IPC::Open2;
my $pid = open2(\*RDRFH, \*WTRFH, './program');
print WTRFH @{$mail[0]};
close WTRFH;
waitpid $pid, 0;
my @array = <RDRFH>;
close RDRFH;