can one admin account have mutliple workspaces? If yes, how many?

understand, but if every workspace is under single account, then is it possible to have lets say 10 million emails/credits per month for a single domain? 5 workspaces with tier 6 = 10 million emails

I see. BTW Tier 6 = 2 million, not 1. Im considering to provide mini ESP service for my clients, but Im concerned about your ToS and other limitations. How can I ensure that one clients bad behavior will not turn into suspending the whole account? Which obviously will effect every other clients accounts. And I do not want that.

when these sending limits (2/sec., 5000/day, 10k subs) can be increased? Lets say that I have a client who has 200k subs and he needs to send 800k emails per month. Could you please tell me the steps (for ex., 5k/day for a week, and then 10k/day for a week, and then 100k/day for a week or something) and most important the time needed, if everything goes perfectly, to reach 800k emails per month?

Since you mentioned that everything is workspace-based, it makes sense to create a separate workspace for each client (1 client = 1 workspace). However, you also said that a single workspace can have a maximum of one Tier 6. So the question is: how can I allocate 2M credits across multiple workspaces?
For example, how would one Tier 6 (2M credits) be distributed across 50 workspaces?

That is a big disadvantage, that you can't allocate credits among workspaces. So my question is How do you prevent ONE bad client from getting the WHOLE workspace suspended?