[Exim] exim - warn users about sending large messages

Hi all,

I don't want to restrict the size of messages my users can send, but I
would like to be able to send them a gentle reminder when outgoing
messages are over a certain size.
E.g "your message [subject or sender name] has been sent, but was over
10Mb in size"


Has anyone done this before? Is it possible?
I use a very simple set of routers as a mail-hub shown below:
---------------
redirect:
driver = redirect
data =
${lookup{$local_part@$domain}lsearch{/usr/exim/exim_redirect_to_list}}

internal:
driver = manualroute
transport = remote_smtp
route_data =
${lookup{$domain}partial-lsearch{/usr/exim/exim_route_to_list}}

external:
driver = manualroute
domains = ! +relay_to_domains
transport = remote_smtp
ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
route_list = * my-mailscanning.service.com
no_more
-----------------

Thanks in advance,

Jason Meers

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