The "load balancing" conundrum.

Here's the issue: your client has X amount of mail, and he wants to get 100% delivered simultaneously, or as close to that as possible. The receiving ISPs say, "Until you are known, or have good reputation (depending on the ISP's policy), we will only accept Y, a fraction of X, from any single IP address." ISPs have policies like this in place to protect their customers from senders who do not engage in best practices and to protect their infrastructure from abuse and overloading.  Instead of respecting that limit, your client says, "Give me enough IPs to send out all of my mail to a given ISP at once." Both you and the client know the client doesn't need all those IPs long term; they only need to send from that many IPs until they become known or good, so they can push all their mail at once. It is disrespectful of the ISPs, and purposefully attempting to get around ISP policies may be perceived as abusive behavior. What do you do? Do you supply the customer with far more IP addresses than what is actually needed, allowing the client to send without earning the trust and good reputation necessary to send their full volume in a small window, or do you advise your client to scale back and ramp up by sending from a more appropriate number of IPs, taking the time to send engaging mailings to recipients from whom they have explicit permission?