In my initial code
$wgSMTP = [
'host' => 'mail.[domain]',
'IDHost' => '[domain]',
'port' => 587,
'auth' => true,
'username' => '[username]@[domain]',
'password' => '[password]'
];
I just changed the 'host' => 'mail.[domain]' to host' => 'x12.x10hosting.com' and MediaWiki...