Hi,
I have set up under spam filters to block email about 3mb and drop it. However, is there a way to configure it such that the sender will receive an automated email saying that the file sent is too big? Pls advise. Thanks.
You'll either have to configure exim.conf to block emails over a certain size (I think this can be done but I've never studied it) or make changes to the exim.pl file to send the email when it detects the larger file and drops it.
However, either would be non-supported changes and then you'd have to support the files into the future.