MSMQ messages using HTTP just won't get delivered #7
Here's one I've copied from the Motley Queüe Blog for Windows 2008 so its a bit early.
MSMQ’s transactional message support uses internal messages called “order ACKs” to coordinate between sender and receiver so that no user messages are lost. When transactional messages are sent via HTTP, the URLs used to send the order ACKs back to the sender sometimes contain the special character “+”. IIS 7 has a security feature in request filtering to disallow all double escaped characters, and this interferes with the return of order ACKs to the sender if the URL contains a “+”. This results in the transactional messages accumulating in the outgoing queue of the sender in those cases. In order to prevent this issue, which may arise any time transactional messages are sent via HTTP, you can disable the double escaped character filtering in IIS7 for MSMQ’s virtual directory. This can be done using the appcmd tool like so:
%windir%\system32\inetsrv\appcmd.exe set config "Default Web Site/msmq" -section: system.webServer/security/requestFiltering -allowDoubleEscaping:true -commitpath:apphost