Happy New Year, gid! Thanks for the tip. It works.
However, I suggest adding nl2br to 'body'=> to parse new lines as line breaks by default. Otherwise you have to set all <br /> tags by yourself...
Change from:
'body' => trim(qa_opt('mailing_body'))."\n\n\n".qa_lang('users/unsubscribe').' '.$unsubscribeurl,
to:
'body' => nl2br( trim(qa_opt('mailing_body'))."\n\n\n" ).qa_lang('users/unsubscribe').' '.$unsubscribeurl,
all the best,
Kai