Post-delivery agents are designed by default to run on the home mail server of the agent signer (the person who last modified the agent). Before the agents run, they perform a check to see if the current server is the home mail server of the agent signer. The home mail server is determined by taking the name of the agent signer, performing a lookup in the Domino Directory, and retrieving the mail server from the user's Person document. If the home mail server is not the same as the server on which the agent is attempting to run, the agent does not run. This means that the post-delivery agent does not run unless it resides on the user's mail server.
You can change this default behavior by setting the NOTES.INI AMgr_DisableMailLookup variable to 1.
This setting suppresses the check for the user's home mail server and allows the agent to run on any server.