In my experience the best option is to use tools that integrate with your cloud mail provider (G Suite, Office 365) and can send out anywhere between 50 and 500 mails per day.
Examples that I have used are: MailShake & Lemlist. Both are good at what they do. I think it’s a matter of personal preference which one you should choose so I suggest trying both. (I do find Mailshake’s calendar and scheduling options more user friendly)
I have to point out that I’ve had campaigns with 1.000 recipients that have done way better than campaigns with 30.000 recipients. The key difference was this:
- In the small campaign, we used Mailshake and sent 50–100 mails per day (This is what a regular user could do in a day if they were composing emails for 8 hours)
- In the large campaign we blasted 30.000 emails in a matter of hours (through Sendgrid). This is not something a real user would do, with the exception of newsletters. But what do newsletters have, that a single blast campaign doesn’t? The newsletter subscriber list grows gradually, and the subscriber has already interacted with and thus whitelisted the sender.
Protecting your email reputation is very important and it’s definitely a case of quality over quantity.