[Exim] max message size

Hello,

im looking for a way to configure the filter to allow spezific user to
allow reveice/send to/from unknown users.

At the moment i use for global restictions:

if $message_body_size above "${lookup{$sender_address} lsearch*@
{/etc/exim/max_msg_sizes}{$value}}" then
    fail text "Sorry, but your message is too big. You may only send
${lookup{$sender_address} lsearch*@
{/etc/exim/max_msg_sizes}{$value}} bytes."
endif

But the problem is, when i put a user inside "max_msg_sizes" he can send
bigger messages, but when he receives
messages from an unknown sender, the default size and not the size for the
spezifik user is the relevant.

So i look for somethink like (in my own words):

if $message_body_size not in ${lookup{$sender_address} lsearch*@
{/etc/exim/max_msg_sizes}{$value}} or not in
${lookup{$reply_address} lsearch*@ {/etc/exim/max_msg_sizes}{$value}} then
use default

Thanks for help
Bjoern Ramann