If you're having issues with spam replies being sent to your Substack address, the verified subscribers setting can help. When enabled, you’ll only receive post replies and emails from verified subscribers to your subdomain@substack.com address. When an unverified subscriber attempts to send you an email, they’ll be prompted to download the app in order to contact you.
To enable this feature:
1. Navigate to your publication's Settings and click on Community in the left navigation bar.
2. Select the drop down menu to the right next to "Who can reply to your emails?"