[Exim] Executing code after successful transport

Hi.
I have a block of perl code that I would like to execute after the
successful transmission of a message to a remote host.

This would be done in the remote_smtp transport. I'd like to be able
to execute something in the form of ${perl{sizemail}}. I would need
the headers of the message just delivered available for use in the
perl script.

Essentially, I am tracking the amount of email delivered in a database
based upon domain name. The database can ONLY be updated upon
successful transmission of the message. Does anyone have any ideas on
a good way to do this?

Thanks,
Tom Daly