- Turn off the default MailChimp welcome email (if you haven't done so already) for the list.
- Ensure every form that captures a new MailChimp subscriber includes the appropriate signup source.
Create a Welcome Message Automation Workflow with segmentation conditions set to the organic signup source(s). Note this may be a subset of signup sources (e.g. header, footer, popup, etc.) depending on what you are sending as a signup source. In this case add multiple segmentation conditions on Signup Source
where subscribers match ANY (not ALL).