[exim] daemon_smtp_ports

Hello

I am using following 2 lines in top of exim.conf

local_interfaces = 127.0.0.1
daemon_smtp_ports = 125

It proxies to my antispam filter (ASSP) over the port 125 ALL the email received from internet .
It works ok , however I would not pass to my antispam ALL the email , but ONLY the email
which have an email size lower than 256000 bytes .

Is there a way to do that ?

Thank you
Graziano