How to get raw subject ?

[abcprintf]

Hello, I need get raw subject but I can't find how to get raw subject.

ทดสอบ นำส่งจดหมายผ ??�?????�????????�??�???????????????

expected :
ทดสอบ นำส่งจดหมายผ่านระบบอีเมล

but if i can retrieve get raw header subject It will work.

simple :

I'am try:

$subject_raw = "=?UTF-8?B?4LiX4LiU4Liq4Lit4LiaIOC4meC4s+C4quC5iOC4h+C4iOC4lOC4q+C4oeC4suC4ouC4nA==?=
                =?UTF-8?B?4LmI4Liy4LiZ4Lij4Liw4Lia4Lia4Lit4Li14LmA4Lih4Lil?=";
echo mb_decode_mimeheader($subject_raw);

// output : ทดสอบ นำส่งจดหมายผ่านระบบอีเมล  <-- is work

Version:
Laravel 8, php 7.4

[robis199]

$message->getSubject()[0];