[Exim] action on locked mail

Hi all,
my question is about how could I remove a recipient when a mail is being
locked? Or if it's possible to put it in the mail queue (froze,...) and
after remove the recipient.
I get "Spool file is locked" when I execute "/usr/sbin/exim -Mmd
19vBR4-0004Z2-00 unknown@???".

Thanks

Regards