TL;DR - Based on your calculations you are considered a high volume sender and would be a candidate for a dedicated IP address in AWS SES
I was unable to find a source where AWS specifically enumerates what they consider to be high volume e-mail sending. Other sources vary (or are vague) about what they consider high volumes (see references below). From those sources I think you can safely say 100k e-mails a month is the high volume threshold.
Note that there are several pros and cons to using a dedicated IP address that you should consider as well.
- Good for high volume senders
- Your reputation will be your own
- Your IP is more likely to be safe-listed by ISP's
- You can isolate your reputation by e-mail type, recipient, etc.
- The IP address will never change
- It requires additional setup and time to build reputation (and keep it)
- You manage your own reputation
- Not good for unpredictable sending patterns
- Additional monthly cost
Your dedicated IP address needs to warm up before it will be accepted. You'll also need to keep a steady volume to maintain that reputation.
For each ISP with which you want to cultivate a reputation, you should send
several hundred emails within a 24-hour period at least once per month.
Finally a couple of caveats I saw in the AWS SES Developers Guide:
If you don't plan to send large volumes of email on a regular and predictable basis, we recommend that you use shared IP addresses. If you use dedicated IP addresses in situations where you're sending low volumes of mail, or if your sending patterns are highly irregular, you might experience deliverability issues.
Although there's no minimum commitment, we recommend that you lease more than one dedicated IP address in each AWS Region where you use Amazon SES....When you lease more than one dedicated IP address, we distribute those addresses as evenly as possible across the Availability Zones in the AWS Region that you specified in your request. Distributing your dedicated IP addresses across Availability Zones in this way increases the availability and redundancy of your dedicated IP addresses.
AWS SES Developers Guide
Dedicated vs Shared IP addresses - How they affect email delivery
How to Send High Volume Email
Dedicated vs. Shared Email IP