I've installed MailInContrib version 2329 (03 Feb 2009) and copied this working configuration from twiki 4.2.3:

$Foswiki::cfg{MailInContrib} = [
          {
                                 'onError' => 'log,reply,delete',
                                 'user' => 'guest',
                                 'onSuccess' => 'log delete',
                                 'topicPath' => 'subject',
                                 'folder' => '/var/www/.maildir/',
                                 'spambox' => 'Main.SpamBox',
                                 'onNoTopic' => 'spam'
          }
        ];

and when I submit a message to foswiki, it always replaces %WIKIUSERNAME% by something like Main.ARRAY(0x8cc6214). It happens only when I send the mail from mail address that is known to foswiki (found in my personal data). If I send it from other address, it replaces %WIKIUSERNAME% by Main.guest correctly.

-- JurajVariny

Seems fixed in 1.0.4, set CurrentState accordingly.

-- JurajVariny - 29 Mar 2009