Interesting letter, can you figure out what it is?

Question

Email

Here is a letter that a colleague received in the mail today. What is it?
I removed the addressee and the domain. I took the original letter in text form.
Who has any ideas?

Received: from mta1.e-proxa.com ([217.23.139.191])
  by isp.cloud.iskrakb.ru with esmtp (Exim 4.92.3)
  (envelope-from <[email protected]>)
  id 1kNqeL-0003B9-QH
  for [email protected]_________.ru; Thu, 01 Oct 2020 11:57:02 +0700
From: <[email protected]>
To: <[email protected]_________.ru>
Subject: UAKYQBZGK KASTONWXH
Date: Thu, 1 Oct 2020 04:53:35 +0700
MIME-Version: 1.0
Content-Type: multipart/alternative;
  boundary="----=_NextPart_000_003E_01D69986.D7784860"
X-Mailer: Microsoft Outlook 16.0
X-Scanned-By: ClamAV 0.101.5; Thu, 01 Oct 2020 11:57:01 +0700
thread-index: AdaXr0zxxFTcipfrQ4mTPfMzsEdTTg==
Authentication-Results: dkim=pass, [email protected]@e-proxa.com
Authentication-Results: dkim=pass, [email protected]
X-Spam_score: 2.0
X-Spam_score_int: 20
X-Spam_bar: ++
X-Spam_report: Spam detection software, running on the system "isp.cloud.iskrakb.ru",
 has NOT identified this incoming email as spam.  The original
 message has been attached to this so you can view it or label
 similar future email.  If you have any questions, see
 the administrator of that system for details.
 
 Content preview:  3HXT40ONGO2JCPHUO0A610GJF5 YNTL 6 QM8O0SK8HUFEL1GFF SDGZWS9
    WT7OFUJ3YR8DBJIO1Y2MX57ANLUYUJE0QT7USV1 [...] 
 
 Content analysis details:   (2.0 points, 5.0 required)
 
  pts rule name              description
 ---- ---------------------- --------------------------------------------------
  0.5 SUBJ_ALL_CAPS          Subject is all capitals
 -0.0 SPF_PASS               SPF: sender matches SPF record
  0.0 SPF_HELO_NONE          SPF: HELO does not publish an SPF Record
  0.0 HTML_MESSAGE           BODY: HTML included in message
  0.7 MPART_ALT_DIFF         BODY: HTML and text parts are different
  0.1 MIME_HTML_ONLY         BODY: Message only has text/h
  tml MIME parts
 -0.1 DKIM_VALID_AU          Message has a valid DKIM or DK signature from author's
                             domain
 -0.1 DKIM_VALID             Message has at least one valid DKIM or DK signature
  0.1 DKIM_SIGNED            Message has a DKIM or DK signature, not necessarily valid
  0.1 MISSING_MID            Missing Message-Id: header
  0.6 HTML_MIME_NO_HTML_TAG  HTML-only message, but there is no HTML tag
  0.0 MIME_HTML_ONLY_MULTI   Multipart message only has text/html MIME parts
  0.0 TVD_SPACE_RATIO        No description available.

This is a multipart message in MIME format.

------=_NextPart_000_003E_01D69986.D7784860
Content-Type: text/plain;
  charset="us-ascii"
Content-Transfer-Encoding: 7bit

3HXT40ONGO2JCPHUO0A610GJF5 YNTL 6 QM8O0SK8HUFEL1GFF SDGZWS9
WT7OFUJ3YR8DBJIO1Y2MX57ANLUYUJE0QT7USV1

------=_NextPart_000_003E_01D69986.D7784860
Content-Type: text/html;
  boundary="===============3559961448112974035==";
  charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

3HXT40ONGO2JCPHUO0A610GJF5
 YNTL
6
QM8O0SK8HUFEL1GFF
SDGZWS9
WT7OFUJ3YR8DBJIO1Y2MX57ANLUYUJE0QT7USV1
------=_NextPart_000_003E_01D69986.D7784860--

My assumptions:

• a letter to control a bot or trojan;
  
• a letter from a prospective employer who is looking for talent, this has already happened in the history of IT /
  

Answer 1

What is the purpose of this letter? Spam came, antispam software showed extra statistics why it thinks it is spam.