Sending Emails via PEAR::Mail - Russian chars in subject line

We're running an email application that operates in multiple languages. So far all has gone well but we've just taken on a Russian customer and we've found that email subject lines are coming through blank.

The same code is used for all languages and the entire site & db uses UTF-8 all the way. German, Italian, Polish, etc. all work, it appears to be only Russian.

At present we're setting the 'head_charset' parameter to be 'UTF-8' - might the solution to be to use some form of Unicode for Russian?

Any advice or recommendations welcomed.

 

$subject = "Заголовок с русскими буквами - subject with russian letters";
$subject = '=?utf-8?B?'.base64_encode($subject).'?=';

PHP:

then use $subject in mail() funtion

I don't know where you do set this param, but I use code above to send mail with russian subject.