Ouch! can you trust all those email apps to map the same content to the same content-mime-type consistently?

In the meantime I went back to Email::MIME and had good results (for my one multipart test email) with its walk_parts().

        my $client = Mail::IMAPClient->new(...);
        # ... search mail box
        my $parsed = Email::MIME->new($client->message_string($msgid))
+;
        my @parts_to_save;
        $parsed->walk_parts(sub { push @parts_to_save, $_[0] });
        # the [0] is the whole message, rest are all parts including n
+ested
        for (@parts_to_save){ print $_->as_string }
[download]

Email::MIME has also a t/nested-parts.t which I used to check that it works fine for nested parts.

And it seems I am leaving the dreadfull world of email.