Rebuilding Email Infrastructure: Options for Domains and Inboxes

13 domains and 50 Inboxs are marked as spam after using a well known SMTP provider Now I need to rebuild the whole thing to be able to send 500 emails a day and have a back up set up to do the same I estimate we need 10 domains and 10 back up domains 20 inboxes each sending 25 emails a day and 20 back up inboxes just warming up There are so many options I don't know where to start... Buy inboxes and domains direct from Instantly? Do the whole manual gig and buy Microsoft and Google inboxes? Buy inboxes from hypertide? Budget is no issue but I have to do all the work as I have no VA at this particular job