Why is this letter coming?

Question

opencart

Good afternoon. I downloaded the distribution module for ocstore 2.3 - everything works fine, except for one. I receive letters on openserver in this format, that is, the text itself is not displayed. What needs to be done or where to look to fix this? Not strong in php. Is there such an option that everything will be fine on the hosting itself?

To: [email protected]
Subject: =?UTF-8?B?MTIz?=
X-PHP-Originating-Script: 0:mail.php
MIME-Version: 1.0
Date: Sat, 24 Apr 2021 16:48:24 +0300
From: =?UTF-8?B?0JzQvtC5INCc0LDQs9Cw0LfQuNC9?= <[email protected]>
Reply-To: =?UTF-8?B?0JzQvtC5INCc0LDQs9Cw0LfQuNC9?= <[email protected]>
Return-Path: [email protected]
X-Mailer: PHP/7.2.0
Content-Type: multipart/mixed; boundary="----=_NextPart_2ceb90e453f10eddd02c080221c02efa"

------=_NextPart_2ceb90e453f10eddd02c080221c02efa
Content-Type: multipart/alternative; boundary="----=_NextPart_2ceb90e453f10eddd02c080221c02efa_alt"

------=_NextPart_2ceb90e453f10eddd02c080221c02efa_alt
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit

This is a HTML email and your email client software does not support HTML email!
------=_NextPart_2ceb90e453f10eddd02c080221c02efa_alt
Content-Type: text/html; charset="utf-8"
Content-Transfer-Encoding: base64

PGh0bWwgZGlyPSJsdHIiIGxhbmc9ImVuIj4KICA8aGVhZD4KICAgIDx0aXRsZT4xMjM8L3RpdGxl
PgogICAgPG1ldGEgaHR0cC1lcXVpdj0iQ29udGVudC1UeXBlIiBjb250ZW50PSJ0ZXh0L2h0bWw7
IGNoYXJzZXQ9VVRGLTgiPgogIDwvaGVhZD4KICA8Ym9keT48cD4xMjM8L3A+PC9ib2R5Pgo8L2h0
bWw+Cg==

------=_NextPart_2ceb90e453f10eddd02c080221c02efa_alt--
------=_NextPart_2ceb90e453f10eddd02c080221c02efa--

Answer 1

It also says "This is a HTML email and your email client software does not support HTML email!"
The content of the html email is base64 encoded. Specifically, in your letter there is the text "123" and that's it.
In a real situation, you will receive a decoded email in HTML format.