Posted this on a few comments because I find them really helpful: https://improvmx.com/
Granted, we don't have chargebacks everyday, but we get some occasionals one that, at these price, would hurt way more.
Now, we still offer an alternative plan that is available only upon request (or on certain occasions). We call it the "Lite plan" at 30$ per year, where you have all the advantages of the premium plan, but without the SMTP sending part. If that interests you, just send a request to the support and we'll enable it for your account :=)