Problem sending DLA and AA forms

I think many of us have been advising clients to CONSIDER spending a few quid and sending their application forms “Signed For”, so that they have a reference number and (hopefully) proof of delivery, in case the form gets lost.

These days both the return envelopes and the form themselves have the addresses:
- Freepost DWP DLA Child
- Freepost DWP Attendance Allowance
The AA form also gives this warning “Do not send this form to any other address as we may not get your claim.”
Note that neither of these addresses include a post code

I’ve had several incidents recently of Post Offices refusing “Signed For” letters without a post code. The best they can offer is a free receipt - which is proof of POSTING, not proof of DELIVERY. So not so valuable when it comes to an MR about date of claim.

3 questions:
- Is it correct that items without a postcode can’t be sent Signed For?
- If not, any suggestions on how to convince counter staff that they can?
- Any work-arounds?

Thanks in advance for your help