[exim] Outbound mail rate limiting

Hello All,

novice exim user here. I set up exim some time ago for a client, that
needed some mail header rewrite functionality. Exim is set up as an
smtp relay - it excepts e-mail form exchange server, rewrites the
header - and forwards it to the ISP SMTP.

The ISP recently configured rate limiting on its side, so now I need a
way to limit outgoing SMTP messages so I can match the ISP
requirements. I googled and I think I need some acl set up, but I cant
figure where or how should I define it. I only found some solutions
for per user or per domain limits, but I would like to limit all
outgoing smtp mail, let's say 8 mails per minute and what is over that
limit gets put in the waiting queue.

I don't know much exim, so If anyone would be so kind to help me
configure exim thank you in advance.

Kind regard,

Uros