If you're finding that bounces aren't being recorded within your Soapbox Mailer campaign record, here's a few things to try in order to make bounces register within your Soapbox Mailer campaign.
1) Ensure that all of your Campaign Member fields for the Soapbox Mailer Site Public Access settings are properly set as listed in the Getting Started With Soapbox Mailer guide.
2) Ensure that your Amazon SNS bounce topic (ses-bounces-topic) is setup: Amazon > SNS > Navigation > ses-bounces-topic
3) Ensure that your Amazon SNS is set to be in the "N. Virginia" (also known as the "US East") region: Amazon > SNS > Dropdown menu next to your name in the upper-right part of the screen.
4) Ensure that your Amazon SES has your campaign's verified sender's feedback details pointed to the proper SNS topics: Amazon > Navigation > Verified Senders > Email Address tab > (click on an email adddress) > Feedback Details > ensure that "Bounces SNS Notification" points to your ses-bounces-topic.
5) Ensure that your Soapbox Mailer Email Service has an active licensed Context User.
a) Login to your Salesforce account, and go to Setup > Develop > Email Services
b) On the "Email Services" page, click on the Email Service Name "sbx_EmailAWSResponseHandler"
c) On the "Email Service: sbx_EmailAWSResponseHandler" page, under the Email Addresses section, click the "Edit" link next to the one email address listed
d) On the "Email Service Address" page, under the Email Address Information section, for the Context User, choose an active Salesforce user (this does not need to be a System Administrator profiled user)
e) Click the Save button
6) Ensure that your Amazon SNS topic end-point for ses-bounces-topic is the same as your Salesforce Email Service Address. For more on your Salesforce Email Service Address, check out Step 1: Create a Salesforce Email Service.