[Exim] Frozen messages ...

I think I saw somewhere inside exim's manual's that there is a way to be
notified when a message is frozen ... Could someone tell me what option to
use, I can't find it again ?

Thank's in advance !

Georges

PS : Here is another newbie question ... I created an exim user and group
... The trouble I have is that, when using local mail (/bin/mail), procmail
changes the spool files mode from 660 to 600 ... Is there a way to change
that ?