[SalesForce] Web-to-lead (W2L) not working after switching web form to ‘webto’ URL

On my local development PC, I've updated the W2L (web-to-lead) url for our web form that puts leads into our production instance of salesforce. This is required because the old URl that forms are submitted to (
https://www.salesforce.com/servlet/servlet.WebToLead) is being retired on Friday. I've updated the URL to
https://webto.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8. The leads aren't going into salesforce now (the form is working fine though on our production website, which uses www.salesforce.com).I added the following to our HTML form:

and the output I get after posting to the webto.salesforce.com URL is:

Record Information:

00N90000001ebDD: Melbourne
URL: test
company: Test
debug: 1
email: me@me.com
encoding: UTF-8
first_name: Chris
last_name: 
lead_source: Web2Lead
oid: 123ourOrgId
phone: 0449188123
retURL: https://localhost/abc
submit: 

When the host was originally www.salesforce.com instead of 'webto.salesforce.com', adding a lead to salesforce worked, but if I now change it back to www.salesforce.com it doesn't work any more! Here's the output I get now when posting to www.salesforce.com:

Your request has been queued.

Record Information:

00N90000001ebDD: Melbourne
URL: Test
company: test
debug: 1
email: me@me.com
encoding: UTF-8
first_name: Chris
last_name: Test3
lead_source: Web2Lead
oid: 123OurProductionId
phone: 5555555555
retURL: https://localhost/blah
submit:   

Best Answer

After changing the URL on a web-to-lead web form, leads can be queued. This is what was happening, so the leads didn't immediately make it through to salesforce. When the leads did get sent to salesforce, the leads weren't added as I was using the same email address each time, and our Salesforce only allows one lead to be created per email address.