While doing so, a colleague, Andrew Cooper, reminded me that permissions on the econnect_incoming queue has caused problems in the past. Navigating to the econnect_invcoming Properties window () which contains a message at the bottom stating;
“Queue is unauthenticated. Message senders can bypass the Access Control settings specified in the Security tab.”
Despite this message, I switched to the Security tab and set the Everyone permissions to Full Control (this is an internal server which is not accessible to the outside world);
After making this change, the client was able to post messages to GP using eConnect. Based on the message at the bottom of the General tab there must be something else going on, but changing the permissions did resolve the problem.
If anyone can shed light on why changing the permissions helped when the General tab message suggests it won’t I’d appreciate it.