Cold Email: I need to send bulk email for each client

I run a call center. We need to send about 300 emails a day for each of our clients, and we have 10 clients.

We’re trying to figure out which email sender would work, and won’t hit spam. We hear a lot about mailgun. Would that be a good fit?

We definitely understand the DKIM and SPF setup, and warming up the email. We just really need to figure out a way to send bulk email and not go to spam because of volume limits