Hi Dale,
This is a limitation of the workflow, that is, when sending an email in the workflow, the address of the recipient cannot be filled in with a field.
The reason is that the To field is a PartyList type field, and its value is an array of records GUID, and cannot store the value of the field.
So, in this scenario, we have to use Power Automate instead of workflow to send emails.
Go to https://make.powerapps.com/, click Flows > New > Automated—form blank.

Select Trigger as When a record is create, update or deleted. Set the condition as it is in the workflow.

Pay attention that all fields entered in flow are name and no longer display name.
+ New step, select Send an email (V2).

Click To field and click Add dynamics content, select the textfield new_emailadress1.

Then complete the remaining email content. Save the flow.
Then test this flow. Change the activity-state from a client, and see if the flow run successfully.
You can see its test result in the 28-day run history.
