No surprise it doesn't work; it doesn't compile. You were on the right path in the first code. Just send the complete email message with datasend. Most importantly, send the header with To:, From:, Subject:, and blank line separating it from the body.

use strict;
use Net::SMTP;

my $sender = $ENV{USER};
my $recipient1 = 'john@hotmail.com';
my $smtp = Net::SMTP->new('mailhost.com');

$smtp->mail($sender);
$smtp->recipient($recipient1);
$smtp->data();
$smtp->datasend("To: $recipient1");
$smtp->datasend("From: $sender");
$smpt->datasend("Subject: some subject");
$smtp->datasend("");
$smtp->datasend("This is the body");
$smtp->datasend("");
$smtp->quit;
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