I'm trying to send an email (automaticaly, when user register), but I don't get some different letters correct. Here's example code:

$message="Some message that contains č, ć, đ, ž, š"; //on the server, I can't write letters like č, ć etc.; I must write their code & # 269,...

I tried different html codes, like & # x010D, but this also doesn't work. Can somebody help me?
//PS. on the server, if I write letter č it automaticaly change it to & # 269.