PayPal Express requires shipping address for downloadable product

I just switched from PayPal Standard to Express, and it seems to be working okay, but I'm getting "ALERT: 10727 Shipping Address1 Empty - The field Shipping Address1 is required" even when customers order only downloadable products.

My shop correctly recognises them as downloadable (I have them set as "No, Shipping Address Required" and "No, Normal Shipping Rule" so my shop doesn't ask for a shipping address or apply shipping charges) but PayPal still seems to require a shipping address.

Is there a way to turn off the PayPal address checking (either for orders containing only virtual/downloadable products, or altogether)?

Thanks! This is driving me crazy...

Here's the CURL log for an example failed order, in case that sheds any light on the problem (both products in the order below are downloads):

Array
(
[0] => Content-Type: text/namevalue
[1] => X-VPS-Timeout: 45
[2] => X-VPS-VIT-Client-Type: PHP/cURL
[3] => X-VPS-VIT-Integration-Product: PHP::Zen Cart(tm) - PayPal/NVP
[4] => X-VPS-VIT-Integration-Version: 1.3.9e
)

Request Parameters: {DoExpressCheckoutPayment}
Array
(
[AMT] => 10.50
[ITEMAMT] => 10.50
[L_NUMBER0] => MP006
[L_NAME0] => Gecko (lizard) amigurumi crochet pattern
[L_DESC0] => Downloadable: zipped PDF file
[L_AMT0] => 5.00
[L_QTY0] => 1
[L_NUMBER1] => MP002
[L_NAME1] => African Violets crochet pattern
[L_DESC1] => Downloadable: zipped PDF file
[L_AMT1] => 5.50
[L_QTY1] => 1
[SHIPTONAME] => EDITED OUT
[SHIPTOSTREET] =>
[SHIPTOCITY] =>
[SHIPTOSTATE] =>
[SHIPTOZIP] =>
[SHIPTOCOUNTRYCODE] => US
[BUTTONSOURCE] => ZenCart-EC_us
[ADDROVERRIDE] => 1
[RETURNFMFDETAILS] => 0
[CUSTOM] => EC-230-1281402280
[INVNUM] => 230-1281402280-[PlanetJunecom]
[TOKEN] => EC-45E17614VB668061Y
[PAYERID] => DKU2ZJRX7EG2Q
[PAYMENTACTION] => Sale
[NOTIFYURL] => http://planetjune.com/shop/ipn_main_handler.php
[METHOD] => DoExpressCheckoutPayment
[CURRENCYCODE] => USD
[USER] => EDITED OUT_api1.gmail.com
[PWD] => ****************
[VERSION] => 60.0
[SIGNATURE] => ****************************************************IGcM
)

Response:
Array
(
[TIMESTAMP] => 2010-08-10T01:04:40Z
[CORRELATIONID] => 7130625e65d64
[ACK] => Failure
[VERSION] => 60.0
[BUILD] => 1421734
[L_ERRORCODE0] => 10727
[L_ERRORCODE1] => 10728
[L_ERRORCODE2] => 10729
[L_ERRORCODE3] => 10730
[L_SHORTMESSAGE0] => Shipping Address1 Empty
[L_SHORTMESSAGE1] => Shipping Address City Empty
[L_SHORTMESSAGE2] => Shipping Address State Empty
[L_SHORTMESSAGE3] => Shipping Address Postal Code Empty
[L_LONGMESSAGE0] => The field Shipping Address1 is required
[L_LONGMESSAGE1] => The field Shipping Address City is required
[L_LONGMESSAGE2] => The field Shipping Address State is required
[L_LONGMESSAGE3] => The field Shipping Address Postal Code is required
[L_SEVERITYCODE0] => Error
[L_SEVERITYCODE1] => Error
[L_SEVERITYCODE2] => Error
[L_SEVERITYCODE3] => Error
[CURL_ERRORS] =>
)

DoExpressCheckoutPayment, Elapsed: 520ms -- Failure

Help me recreate the problem.

I have a brand new fresh clean install of v1.3.9e.
How do I get from there to exactly reproducing the problem you're experiencing?
Step by step.

This sounds exactly like the issue that Wordpress on Zen introduces. Are you using that mod?

No I'm not :(

Sorry for the delay in replying - I've emailed a customer who experienced this error and then successfully completed the order a couple of minutes later to ask how she got around the problem - this may shed some light on exactly what's happening! I'll reply to your question when I've heard back from her. Thanks!

OK It was just a thought. I haven't looked at the 'why' of the wordpress thing. I just never use that mod as it is so problematic anyway.

Sorry my previous response was a little brief! I appreciate the suggestion anyway - thanks :)

Okay, I think I've pinned down the problem a bit more: I believe it only occurs when people click the Express "checkout with PayPal" button, instead of logging in and going through my checkout pages.

So I'm pretty sure that the problem is that PayPal is requiring an address (listed in the customer's PayPal account) from Express checkouts - i.e. those where the customer is not logged in through my shop - even though all the products in the order are downloadable and I'll never see or need that address.

My customer has verified that this was her problem - when she checked out through Express she got the "address required" error, but when she logged into her shop account first, she could check out successfully through PayPal without being asked for an address. Note: she does NOT have (or need) a billing or shipping address listed in her account with my shop.