my $mailfh;
if ( open($mailfh, '| /usr/sbin/sendmail -t -oi ') ) {
  print $mailfh 'From: test@example.org', "\n",
        'To: admin@example.org', "\n",
        'Subject: ERROR in blah blah', "\n",
        "\n",
        'Error occured in ThisOrThat', "\n",
        "" . localtime(time), "\n",
        '.';
  close($mailfh) or warn ("Mail not sent by sendmail: $!");
} 
else {
  warn ("pipe to sendmail cannot be opened: $!");
}