Mail Flow Settings

Also configurable from the Properties of a mailbox object, mail flow settings can be modified to enable for changes in delivery options, message size restrictions, and message delivery restrictions. Some specifics on the mail flow settings are as follows:

• Delivery Options-Utilizing this tab, administrators can enable other users to Send on Behalf of this user. Messages that are "sent on behalf" show the recipient both who the message was sent on behalf of AND who actually sent the message. Additional settings on the Delivery Options tab can allow the mailbox to forward messages to another mailbox in the organization, and the administrator can specify whether to Deliver Message to Both Forwarding Address and Mailbox. Finally, an option exists to specify the Maximum recipients the mailbox can send to at one time.
• Message Size Restrictions-Administrators can mandate the maximum message size that a user can send or receive, overwriting the settings configured at the organizational level. The Maximum send and receive sizes should generally be the same, or users could have a situation in which they can receive a message but cannot forward it (or reply with the original message attached). Likewise, if the Receive limits are lower than the Send limits, the user might send a message to a fellow employee but not receive a reply that includes the original message.

The default quotas set at the organizational level are

• Maximum receive size (KB)-10,240KB (10MB).
• Maximum send size (KB)-10,240KB (10MB).
• Maximum number of recipients-5,000.

There are several places in an Exchange Server environment in which message size limits can be applied:

• Individual Mailbox Level-Viewed in EMC from the message size restrictions or can be viewed in EMS with the following command:
  Get-Mailbox "username" | fl *size*
• Organizational Level-Viewed in EMC by navigating to the Organization Configuration \ Hub Transport node and select the Global Settings tab. Select Transport Settings object and select Properties from the action pane. Select the General tab to review the settings. Can be viewed in EMS with the following command:
  Get-TransportConfig | fl *size*
• Send and Receive Connectors-Can be viewed in the EMC by navigating to the Organization Configuration \ Hub Transport node and selecting Send Connectors, or by the Server Configuration \ Hub Transport node and selecting Receive Connectors. Can be viewed in EMS with the following commands:
  Get-ReceiveConnector -id "receive connector name" | fl *size*
Get-SendConnector -id "receive connector name" | fl *size*

  Note: Setting a higher message size limit on an Exchange Recipient bypasses the maximum message size settings at the organizational level. However, this is for internal messages only-messages sent outside of the organization are still subject to the organizational limits.

• Message Delivery Restrictions-With this feature, you can dictate whether an individual mailbox can receive messages from all senders or only specified senders, and whether those senders are required to be authenticated. Additionally, you can configure the mailbox to reject messages from particular senders.