Ratelimit for external mail there is none of the major email providers. Your ability to make a large distribution depends on the accumulated reputation of your IP addresses, domains, DKIM, signatures, etc. to Take the base with the emails and start on her mailing list will not work. If earlier you did not do mailings, you no accumulated reputation, you will not be able to do a great newsletter because of the new service can not suddenly legally receive a large number of subscribers.
In situations where it is necessary, for example, has long been to move the existing emails from your ESP for resources - move it gradually - this is called "warm-up". Warming up allows you to accumulate reputation. Try to keep your newsletter contain more authentication information - PTRы, DKIM, SPF, DMARC to "warm up" are different entities, and that the mailing contained as little as possible debris. If you are going to send something bad - reputation, of course, save will not work.
PS here is an article
about how the reputation works in Mail.Ru.