How can I disable incoming e-mail, from outside the organization only, for the HelpDesk mailbox? Yet, I want users to be able to send e-mails to the box for the IT people to answer. Additionally, I want to ensure that HelpDesk mailbox can not send messages outside the organization. HelpDesk mailbox is a group that includes users.

What version of Exch? If 2007 or 2010, you can create a transport rule or change in message delivery restrictions. See link: http://www.msexchange.org/articles_tutorials/exchange-server-2007/management-administration/restricting-users-send-receive-external-messages-exchange-server-2007.html Tim Harrington - Catapult Systems - http://HowDoUC.blogspot.com

Hi Somaji, Based on your description, if your Exchange server version is 2007/2010, you will implement it using transport rule. Condition: from users inside or outside organization Sent to users inside or outside the organization Action: silently drop the message Expect: when the message is from users inside or outside the organization and when any of the recipients in the To field is a member of distribution list For detailed, you can refer the following article, Getting to Know Transport Rules in Exchange 2007: http://technet.microsoft.com/en-us/library/bb421708(EXCHG.80).aspx How to Use Transport Rules in Exchange Server 2007: http://www.msexchange.org/tutorials/Transport-Rules-Exchange-Server-2007.html Restricting Users to Send and Receive External Messages in Exchange Server 2007: http://www.msexchange.org/articles_tutorials/exchange-server-2007/management-administration/restricting-users-send-receive-external-messages-exchange-server-2007.html And for Exchange 2003, you can achieve your goal using SMTP connector, and the article below will help you, Restricting Users from Sending and/or Receiving Mail via the Internet: http://www.msexchange.org/tutorials/MF009.html Restricting Users from Sending and Receiving Internet Mail in Exchange 2003: http://www.msexchange.org/tutorials/MF025.html I am very glad to have a further discussion with you if you have any questions. Best regards, Serena