Possible reason: your host may have disabled the mail() function

I am using code below to send HTML email.

add_filter( 'wp_mail_content_type', 'set_mail_content_types' );
function set_mail_content_types() {
	return 'text/html';
}

But after this code i am getting this error “Possible reason: your host may have disabled the mail() function”

If i remove above ‘text/html’ code then email work fine.

any help?