Here is disscussion and voting on subject:
http://lv.wikipedia.org/wiki/Vikip%C4%93dija:Balso%C5%A1ana/Par_Extension:NewUserMessage_ievie%C5%A1anu

Here are the settings:
$wgNewUserSupressRC = true;
$wgNewUserMinorEdit = false;
$wgNewUserMessageOnAutoCreate = true;

Is there anything you need to complete that?
I am aware of in site configs:
http://www.mediawiki.org/wiki/Extension:NewUserMessage#In-wiki_configuration

Version: unspecified
Severity: enhancement