The two operations you perform in your script, pinging a remote host and sending an email, can and probably should be done from within Perl, using the Net::Ping and MIME::Lite modules. This gives you several advantages:

• The buffering issues you are presently encountering will cease to be a problem;
• No need to create temporary files;
• Flexibility -- a pure-Perl implementation will be much easier to adapt to different situations than a Perl/Unix hybrid;
• Portability -- If you want to run your Ping reporter from Windows, you need something that doesn't rely on Unix system calls.

With that said, consider using something like the following code:

#! /usr/bin/perl

use strict ;
use warnings ;

use MIME::Lite ;
use Net::Ping::External qw/ ping / ;

# Ping all the IP addresses.
my $output = '' ;
while ( <DATA> )
{
    chomp ;
    next unless $_ ;
    $output .= "$_: " . ( ping( host => $_ ) ? 'OK' : 'FAILED' ) . "\n
+" ;
}

# Compose & send the email.
my $msg = MIME::Lite->new(
                           From     => 'somemail@example.com',
                           To       => 'yourmail@example.com',
                           Subject  => 'Ping Report',
                           Data     => $output
                         ) ;
$msg->send ;

__DATA__
888.333.333.33
156.343.333.99
888.323.222.223
888.222.222.111
[download]

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