[exim] lsearch and random numbers

Hello exim users,

I have a big trouble to be solved and I need your help.

My doubt is about lsearch and how to generate a random number range.

Is it possible to get something like this?

${if exists
{/etc/mailips}{${lookup{$sender_address_domain}lsearch*{/etc/mailips}{$value}{}}}{}}

Until here, normal... but, in mailips I would like to have:

host.domain.tld: 192.168.0.${eval:${substr{-2}{1}{$tod_zulu}}%10}

How to make exim 'exec' that expression on lsearch result to return a
numeric value (192.168.0.N)?

How to generate a random number from a range? For example, I need to
generate random numbers from 30 to 112, is it possible?

My problem is because I need to set a range interfaces for a specific domain
only randomly. Why this? Because some mail servers are limiting the number
of emails per day / hour like Hotmail, there is a low cost way to solve this
situation when have free ips.

It's not spam, but the normal daily traffic is high from limits.

Thanks for any help.