Email character encoding

Hi!

I have a problem with the WordPress’s built-in e-mail sender. When my member managment plugin is trying to send the welcome mail, it looks like this: https://i.imgur.com/n5fkoky.png

I’v tried to use dirrerent plugins, and the woocommerce default password changed alert e-mail also in a bad encoding. What should I do?

Thanks for the help!