[Exim] Executing Sql-statement on every delivery

Hi all.

I want to add a Mysql-statement to a certain transport. For every handled
message some statistics (mailsize etc) are logged to the DB.

I wonder how to call the statement from the transport. I thought about
abusing one of the transport options, let say message_size_limit to do the
statement in a lookup which always evaluates to 0 in the end.

Is there a better way to do it?

Regards
....Volker