XFOR: Looping Message in Mail System That Contains DL with Members on Both Sides of the Connector (166654)

SYMPTOMS

A Microsoft Exchange Server distribution list (DL) may contain recipients that exist on both sides of a connector (for example, on a TAO host and in Exchange Server). If dirsync is enabled and propagation of DLs is allowed, the Exchange Server DL shows up in the foreign mail system, usually as an individual recipient within the foreign mail system. If a user on the foreign mail system sends a message to that DL, the DL traverses the connector and be fanned out at the DL's creation point (in this case Exchange Server).

Once DL expansion is completed, Exchange Server attempts to send to all recipients. If one or more of these recipients reside on the foreign mail system, then when Exchange Server attempts to send to these recipients, the connector recognizes that the correlation ID of this message is the same as that of the original message (original DL). The connector detects this as a looping message and a corresponding log entry is written. This is because each message that traverses the connector has a unique correlation ID. During message conversion this ID is extracted and appended to the correlation table. If two instances of a message traverse the connector with the same correlation ID, the connector attributes this to a looping message.