Why does mutt sees Mailman mailboxes as empty?

["M. Fioretti" <mfioretti@xxxxxxxxxxx>]

Greetings,

I've downloaded the gzipped montly archive of a mailing list (with
closed archives, that's why I can't give the direct link) ran with
mailman/pipermail. When I unzip the compressed mailbox, it looks fine
with cat, more and similar pagers. If I run commands like "grep ^To'
or 'grep ^Subject' on it, I see all the senders and subjects
properly.

But if I open it with mutt -f mailbox_file, mutt says it's empty.
What can the reason be, and how should I proceed to see the mailbox?
different mutt settings, removing special characters from the mailbox
(but which ones?)

TIA,
        Marco
        Digital rights writings -> http://mfioretti.com 
-- 
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