[exim] data_acl and spool file

Hello,

in what phase spool file is written into /var/spool/exim/input -directory? Is it available when data_acl is run, or is it done after "local_scan"?

Is there any way to access message data in data_acl (directly or via reference?). Or course my exim is a bit old (4.10) if things have changed afterwards..

Thanks..