客户端程序中的电子邮件文本默认编码不正确

我正在尝试发送一封电子邮件,其中包含utf-8编码的俄语文本和主题。电子邮件正在接收中,当我在gmail的网络界面打开它时,一切都是正确的。但是,当我在“bat”客户端中打开电子邮件时,默认情况下编码不正确(但我可以手动将其设置为utf-8):

Subject: "Hello. Текст"
Body: "test email. Русский текст"

Subject: "Hello. Текст"
Body: "test email. Русский текст"

代码:

#!/usr/bin/perl

use utf8;
use strict;
use warnings;

use Email::Sender::Simple qw(sendmail);
use Email::Sender::Transport::SMTP ();
use Email::Simple ();
use MIME::Base64 qw( encode_base64 );
use open ':std', ':encoding(UTF-8)';

sub send_email
{
    my $email_from = shift;
    my $email_to = shift;
    my $subject = shift;
    my $message = shift;

    my $smtpserver = 'smtp.gmail.com';
    my $smtpport = 465;
    my $smtpuser   = 'user@gmail.com';
    my $password = 'secret';

    my $transport = Email::Sender::Transport::SMTP->new({
        host => $smtpserver,
        port => $smtpport,
        sasl_username => $smtpuser,
        sasl_password => $password,
        debug    => 1,
        ssl => 1,
    });

    my $email = Email::Simple->create(
        header => [
            To      => $email_to,
            From    => $email_from,
            Subject => $subject,
        ],
        body => $message,
    );

    $email->header_set( 'Content-Type' => 'text/html' );
    $email->header_set( 'charset' => 'UTF-8' );
    sendmail($email, { transport => $transport });
}

my $body = Encode::encode('utf-8', 'test email. Русский текст');
my $subject = Encode::encode('utf-8', 'Hello. Текст');
send_email('user@gmail.com', 'user@gmail.com', $subject, $body);