Line 816 of Mail/Box.pm reads: 
$self->{MB_message_type}->coerce($message);

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running the code in the debugger reveals that this is called at the $folder->addMessage($msg); line.

the problem is that create() does not return an object, (even though the docs claim it's a constructor).

To work around the problem: 

Mail::Box::Mbox->create($foldername, access => 'rw');
my $folder = Mail::Box::Mbox->new(folder => $foldername);

[download]
"What should it profit a man, if he should win a flame war, yet lose his cool?"

In reply to Re: Can't use string ("MODULE") as a HASH ref while "strict refs" in use by Joost
in thread Can't use string ("MODULE") as a HASH ref while "strict refs" in use by m5m5m

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