Handling 'Maildir' folder

Hello.

I'm using a 'Mail::Box::Maildir' folder in a long-running program.
The folder should be read for new mail at regular intervals; and be
synchronised (deletion of processed mails) between rounds.

In the init phase, I have:

  my $mb = Mail::Box::Maildir->new( 'folder' => './incoming',
                                 'create' => 1,
                                 'access' => 'rw',
                                 'remove_when_empty' => 0 ) ;

For each run, the relevant part is something like:

  foreach my $msg ( $mb->messages( '!seen' ) ) {
     $msg->label( 'seen' => 1 ) ;
     &process( $msg ) ;
  }
and, in 'process':

  $msg->delete ;

But which method should be used for synchronising and reading new mails?
At first, I tried to do it with:
    
  $mb->open ;

but 'open' is "not implemented for Maildir".
Then:

  $mb->write ;
  $mb->update ; # Also tried '->acceptMessages'

But they don't seem to do what I expect (mail coming in _after_ the program 
is started never gets noticed).

What's the right way to do it?  [Is it that the folder object must be re-created
at each round (using 'new')?]


Best regards,
Gilles