Testing a bulk email service provider for bounce rates means running a controlled trial with a clean segment of your list. You want to see how accurately their system handles hard vs. soft bounces, handles data cleansing, and protects your sender reputation before you commit to sending at scale.
You may want to check whether the issue is related to the email relay, org-wide email settings, or daily sending limits inside Salesforce. In a few similar Flow and notification discussions, configuration mismatches were the main cause of delivery problems.
For larger notification workflows, some teams also use a dedicated Bulk Email Service Provider instead of relying entirely on default mail settings. I recently tested DigitalAka™ with SMTP/API-based integrations and it seemed fairly straightforward for automated email handling.
It could help to run a simple test email first to isolate whether the issue is coming from Salesforce configuration or the external mail service.
