Good Evening: I have a quick question regarding connectors. I hope that some body can shed a light on it. Scenario: I have multiple sites. My Exchange organization is running in mixed mode. Site A (Head Office) is a mixed mode site that contains Exchange Server 5.5 Servers and Exchange 2000 Servers; Site A contains Bridgehead and IMS servers running on Exchange 5.5. Sites B, C, and D are Exchange Server 5.5 sites and are connected with Site A through a Site Connector. Site E and F are Exchange 2000 sites. Which connector should I use to connect Site E and Site F with Site A. Routing Group connector or Site connector? I know that a Routing Group is a new name of an Exchange Site. In a coexistence mode, I have a choice available to use Routing Group Connector or a Site connector. What is the recommendation about connector in an above scenario where Bridgehead server and IMS servers are running on Exchange 5.5 Server. I am using Routing Group Connector to connect my Exchange 2000 Sites (Site E and Site F) with Site A (Head Office) and I am getting following error message Event Type: Warning Event Source: MSExchangeTransport Event Category: Routing Engine/Service Event ID: 951 Date: 15/2/2003 Time: 2:49:20 PM User: N/A Computer: SERVERNAME Description: When sending mail to following address *.3A30ADD0-4275-BA4C-A0D6-7B9FC70C892C, we have found the connector with target domain *.3A30ADD0-4275-BA4C-A0D6-7B9FC70C892C matching destination address exists in DS. However, we have no way of getting there. Possibly, you need to check your topology and add appropriate connectors among Routing Groups. This server just happens to be the first Exchange 2000 server in the Exchange 5.5 Site of a total of 42 sites/7000 users. ADC is up and running, mail is flowing, mailboxes can be moved, the whole bit. The above error is only written to the event log when server is rebooted. After that, it never shows up again. It does show up 42 times (once for every Exchange 5.5 Site) in an Application Event Log. Any idea to resolve this issues? Thank You, Tariq