I have a startup and I want to create awareness about a new online marketplace to its target users. I am a one-person show with a limited budget. I am looking to buy an email list because I want to be able to see the responses and interests, provide follow-on emails to clarify certain capabilities and provide answers to responders. Outlook, gmail and Mac Mail will likely not allow me to send emails to such a large number of emails at the same time.

Does anyone know the limit on emails that I can send with Outlook, Gmail or Mac Mail without having the server reject my email?

Some companies provide subscriptions for providing tools to send bulk emails to 10s of thousands of people on a daily/weekly/monthly basis. Others do the email campaign for me. Neither seem economical and they are targeted at a very large volume of emails. My objective is not to spam and it's very targeted to a limited audience with an educational objective as opposed to trying to sell them something.

Any advice is welcome and appreciated.