Emailing donors

If you recall, our application will have several features, and so far we built 2 out of 3. Now is the time to build the last feature:

• A person can sign-up to become a donor
• An organization can create blood donation events
• Donors receive an email when a new event is created in their city

Sending emails on AWS

There are multiple ways of sending emails on AWS. Each has their own benefits and drawbacks, and we should consider both when choosing a service to send emails with.

Two main options that come to mind are:

• AWS Simple Email Service (AWS SES)
• AWS Simple Notification Service (AWS SNS).

AWS SES is a reliable and scalable SMTP system. It fits our use case because it supports the pay-as-you-go model. When it comes to advanced features, SES supports HTML emails (with graphics, tables and similar), email templates and a reporting system for bounces, deliveries, and complaints; all three of which are very important for your email sending reputation. As for the drawbacks, SES can email up to 50 recipients at a time so a batching logic must be built for it.

Cost? 62.000 emails free per month, $10 for 100.000 emails after that.

One potential solution using SES would look something like this:

• use DynamoDB streams to capture any newly created blood donation events
• when a new blood donation event is created, we fetch all the donors from the city where the donation event will happen
• batch up to 50 donor’s emails and send and invoke SES send_email() function

Before going any deeper into DynamoDB streams, we will focus on the second point from our list above: “when a new blood donation event is created, we fetch all the donors from the city where the donation event will happen”.