PHP-Vers.=[5.6.40-0+deb8u1]

$headers    = [];
$headers[]  = "MIME-Version: 1.0";
$headers[]  = "Content-Type: text/html; charset=UTF-8";
$headers[]  = "From: example <info@example.com>";

$result = mb_send_mail( "info@example.com", "Test", "Hallo", implode("\r\n", $headers) );
if ( !$result ) {
  echo "Nicht gesendet<br>";
}

Statt example.com steht eine gültige Mail-Adresse