How can I prevent out-of-office responses from being returned to distribution lists (DLs) and other mailing lists?

Savvy email users know that having an out-of-office response go out to a mailing list is a definite faux pas. However, Exchange Server versions earlier than Exchange Server 2003 have no way to prevent that from happening when the user turns on the Out of Office Assistant. Exchange 2003, however, supports a new registry entry that changes the Out of Office Assistant's behavior. The Microsoft article "Out-of-Office Messages Are Sent to Distribution Lists That Are in the BCC Field" (http://support.microsoft.com/?kbid=825370) explains how to add and configure the new SuppressOOFsToDistributionLists registry value on an Exchange 2003 server.

After you set the value of SuppressOOFsToDistributionLists to 1, Exchange 2003 won't transmit out-of-office responses when both these conditions are met:

  • The incoming message contains at least one To or Cc recipient who isn't the out-of-office user.
  • The out-of-office user is a Bcc recipient.

This feature also provides more confidentiality when the delivery settings for a mailbox include delivery to an alternate recipient. The alternate recipient receives messages as a Bcc recipient. Previously, the alternate recipient's account would send back an out-of-office reply, revealing—perhaps unintentionally—that messages going to that mailbox were also being forwarded to someone else. With this new feature, alternate recipients won't send back out-of-office responses unless the message arrives with no To or Cc recipients.