sendmail with utf-8 problem

[kolio]

Hello friends
I install oscommerce in server hostmonster.com. I use different encoding for my country - Bulgaria. This is UTF-8. I set up new language in OSC. All is work correctly except sendmail. When send mail with Cyrillic characters recipients receive this: 0JHQu9C40LfQviDQs9C+0LTQuNC90LAg0YHQu9C10LQg0L/RgNC40YHRitC10LTQuNC90Y/QstCw
0L3QtdGC0L4g0L

I change all character set in file PHP.INI this:
[mbstring]
mbstring.language = Neutral
mbstring.internal_encoding = UTF-8
mbstring.http_input = UTF-8
mbstring.http_output = UTF-8
mbstring.encoding_translation = On
mbstring.detect_order = auto
mbstring.substitute_character = long;
mbstring.func_overload = 1

I change files email.php with this:
$this->build_params['html_encoding'] = 'base64';
$this->build_params['text_encoding'] = 'base64';
$this->build_params['html_charset'] = '; charset="utf-8"';
$this->build_params['text_charset'] = '; charset="utf-8"';
$this->build_params['head_charset'] = '; charset="utf-8"';
$this->build_params['text_wrap'] = 998;

But result is the same
What more can i do?
Help please!

[kolio]

In English is the same too. What happend? Can anybody help me?