Recipe7.6.Allowing Large Messages Through Specific Connectors

Recipe 7.6. Allowing Large Messages Through Specific Connectors

Problem

You need to ensure that large messages only go through specific connectors, usually those with sufficient bandwidth for the traffic.

Solution

Using a graphical user interface

1. Open the Exchange System Manager (Exchange System Manager.msc).

2. Ensure that you have enabled viewing of administrative and routing groups (see Recipe 7.3).

3. Expand the organization Administrative Groups target administrative group Routing Groups target routing group.

4. Click Connectors, right-click the desired connector, and click Properties. Click the Content Restrictions tab.

5. If this is a connector you wish to allow large messages through, uncheck the Only messages less than (KB) checkbox. Otherwise, check it and fill in the value of the largest message you wish to allow through this connection.

6. Click OK.

Discussion

In Exchange 5.5 the SMTP connector did not support the 8-bit SMTP extensions; any binary attachments that went through the IMS had to undergo a conversion to 7-bit format, causing a notable increase in reported size and bandwidth usage. It was common practice to restrict large messages from traversing the IMS, letting them route through an X.400 connector.

In Exchange 2000, this design feature was changed. SMTP connectors and RGCs can transmit binary attachments using the 8BITMIME and CHUNKING extended SMTP features. A common design feature in many deployments is to create connectors to allow direct traffic between two sites over a low-bandwidth link, restricting it to small messages. A second set of connectors is then used to pass larger messages at regular intervals, or over higher-bandwidth links that use less direct routing. This arrangement is more complicated than the Use different delivery times for oversize messages option on connectors, but can ensure that an organization with redundant routing paths reserves low-bandwidth links for smaller messages while permitting bulky attachments to travel a more roundabout path over higher bandwidth links.

See Also

Recipe 7.1 for creating SMTP virtual servers, Recipe 7.3 for RGCs, and Recipe Recipe 7.4 for SMTP connectors