Symptoms
PayPal payments are successfully placed but are left in the Hold status. The log shows that the verification requests fails with an error:
Verification Response:
<HTML><HEAD>
<TITLE>Access Denied</TITLE>
</HEAD><BODY>
<H1>Access Denied</H1>
You don't have permission to access "http://www.paypal.com/cgi-bin/webscr" on this server.<P>
Reference #ID
</BODY>
Cause
PBA does not pass User-Agent HTTP header, which is a bug with id #PBA-62249, planned to be fixed in the nearest product update.