Exchange + RoundCube + attachment name encoding?

Question

Character encoding

Good day, dear ones.
I unrolled the RoundCube, screwed it to the Exchange, the flight was normal except for one minus.
When sending an attachment with Cyrillic in the name via Exchange, the file name is recoded into abracadabra.
This problem is observed during transmission:
* exchange user -> exchange user
* exchange user -> external mail server user
No problems are observed in this combination:
* external mail user (gmail + Thunderbird) -> exchange user
I went to Google, but a meaningful solution I didn't find it, but maybe I didn't understand =)
How to win?
Thanks in advance =)

Answer 1

In the roundcube settings: config/main.inc.php
There are the following lines:

// Encoding of long/non-ascii attachment names:
// 0 - Full RFC 2231 compatible - default
// 1 - RFC 2047 for 'name' and RFC 2231 for 'filename' parameter (Thunderbird's default)
// 2 - Full 2047 compatible
$rcmail_config['mime_param_folding'] = 2;

I was helped by a change to 2, what is your cost?