Don't ask me why, but the
Mail::Box documentation appears to be wrong somehow, or perl's behaviour has changed while the documentation hasn't.
$message is a
Mail::Box::Mbox::Message object, which can't be printed directly.
Use
$message->print(), or
$message->head() and
$message->body() if you need a scalar.
I think some older perl parsed
print $folder->message(0) as
$folder->message(0)->print, but it does
CORE::print($folder->message(0)).
2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$