[exim] Any way to implement an incoming SMTP time limit?

Hi

I've set smtp_receive_timeout in an attempt to limit the time an incoming connection can stay active - this works as designed - however this timer is reset whenever any new data comes in - I'd like to set a maximum connection time - so that when an incoming connection is established it has a finite amount of time to get the job done - otherwise it gets disconnected - is there a known way to do this?

Regards

Julian