Auto-Submitted: auto-generated; type=acme
  Date: Sat, 5 Dec 2020 10:08:55 +0100
  Message-ID: <A2299BB.FF7788@example.org>
  From: acme-generator@example.org
  To: alexey@example.com
  Subject: ACME: LgYemJLy3F1LDkiJrdIGbEzyFJyOyf6vBdyZ1TG3sME=
  Content-Type: text/plain
  MIME-Version: 1.0
   
  This is an automatically generated ACME challenge for email address
  "alexey@example.com". If you haven't requested an S/MIME
  certificate generation for this email address, be very afraid.
  If you did request it, your email client might be able to process
  this request automatically, or you might have to paste the first
  token part into an external program.