Troubleshooter: Controlling Out-of-Office Message Behavior

We've noticed some odd behavior with Exchange Server's out-of-office messages. Specifically, when someone includes a distribution list (DL) in a message's Bcc field, if anyone on the DL has activated the out-of-office function, the sender receives an out-of-office message. How can we control this behavior?

The functionality you describe makes sense; after all, when you send a message, you typically want to know whether the recipient is around or out of the office. However, sending out-of-office messages to all the DL members is an iffy proposition, even more so when the DL is a Bcc recipient. Exchange Server 2003 lets you turn off this feature by creating a new REG_DWORD value named SuppressOOFsToDistributionLists under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem registry subkey. Set the new value to 1. With this parameter set, messages sent to a DL as a Bcc recipient will no longer trigger out-of-office messages if any DL members are out of the office. The Microsoft article "Out-of-Office Messages Are Sent to Distribution Lists That Are in the BCC Field" ( describes this key in greater detail.

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