[exim] raw mime_filename

Hi.

How can I get "raw" $mime_filename ?

In Exim - "headers_charset = UTF-8".
And if file name of attachment not in utf8 i have a problem with log
display.
Example from log, $mime_filename:
"▒▒▒▒▒▒ ▒▒▒ 12_10_22.xlsx"

I could use ... embedded Perl (use Encode).
If i got raw mime_filename ...

Or can you recommend an easier way get filename in log in utf8 encoding?