You receive email each time a Web-to-Lead record is created

If the default lead creator is receiving emails each time a new Web-to-Lead record is created, it's because the debug code in the HTML of your form has been uncommented. The email is the same to the “Default Leads Creator” user’s email address at the time generation of the form.

The debug code in a standard web to lead form looks like this:

<!--  ----------------------------------------------------------------------  -->
<!--  NOTE: These fields are optional debugging elements.  Please uncomment   -->
<!--  these lines if you wish to test in debug mode.                          -->
<!--  <input type="hidden" name="debug" value=1>                              -->
<!--  <input type="hidden" name="debugEmail" value="youremail@yourdomain.com">   -->
<!--  ----------------------------------------------------------------------  -->

Note: Web-to-Case: When a new case is created, an email notification can be sent to support agents or a support queue using Salesforce Flow.

Both features help automate the process of capturing and managing customer interactions, ensuring timely follow-up and efficient handling of inquiries and support requests.