We've built Soapbox Mailer to be an affordable and easy-to-use mass email service for organizations using Salesforce. To determine your pricing, you'll need to take into account a few things.
1) Review our pricing page
2) Determine your monthly license fee. If you are a 501c3 non-profit, choose the plan that meets your annual revenue number from your most recent 990 tax form. For everyone else, use the business plan.
3) Estimate the number of emails (the number of recipients that will receive emails from you multiplied by the number of emails you send) in a month. Then, multiply this by $0.10 / 1,000 to get the variable cost from Amazon SES for email sending.
Enjoy the cost savings and happy emailing!