When user sends a new topic or post, he is redirected to the right place using file go.html in the template folder. In some cases that meta redirection is not working well. Problem occurs when user is surfing with mobile phone or something. So, my question is, can that redirection be done using PHP redirection? I mean that something like this insied go.html:

<?php header('Location: $meta_relocate'); ?>

Is there a simple way to make this work in that template?

Hmm, I believe you have set up such method of redirection manually, setting up $metaLocation option of setup_options.php, right?

By default, it should be switched off. In general, such option should be modified only if you meet problems with default miniBB redirection. Which is EXACTLY about sending headers :-)

I'm using some old version that has in setup_options.php that $metaLocation like this:

//$metaLocation='go';

So does this mean that the system is trying to use PHP's header thing? :-] Some users in my forum complain about blank white page after sending message. That blank page I believe is go.html.

No, blank page could be some error report you don't see, because you have showing errors switched off in PHP. Try to switch them on and investigate, what these users could meet.

go.html isn't a blank page, it contains ">>>" mark at least (and if it's used, it should contain some advanced customized text about redirection, so you should edit it before usage), and if this setting is disabled, exactly, it means, miniBB is not using it at all, but trying to redirect with its standard methods.