set message size limit in microsoft exchange server

[jominj]

Email size restriction in exchange server plays an important role, it will helps in restricting the network bandwidth usage and mailbox size. But the messages exceeding the size will bounce back to the sender itself. So its very important to set the correct size limit as per the requirement.

The email size restriction for user mailbox will be applied in the following order:

    1. Global Transport configuration setting
    2. Connector Settings
    3. SMTP virtual server setting
    4. User mailbox setting

Global Transport configuration settings

This setting determines the maximum size of the messages in the Exchange organization; the messages can be incoming, outgoing, or internal.
To configure the global setting, follow these steps:
     

• Start Exchange System Manager. Goto-> Start -> Programs -> Microsoft Exchange -> System Manager.
• Expand Global Settings.
• Right-click Message Delivery, and then click Properties.
• Click the Default tab to configure the global settings.

Connector Settings

The settings for each connector control the maximum size of outgoing messages that users can send through the connector.
To configure the connector settings, follow these steps:
   

• Goto Start -> Programs -> Microsoft Exchange -> System Manager.
• Expand Administrative Groups, and then expand Administrative Group Name, where Administrative Group Name is the name of your administrative group.
• Expand Routing Groups, and then expand Routing Group Name, where Routing Group Name is the name of your routing group.
• Expand Connectors, right-click the connector that you want to configure, and then click Properties.
• On the Content Restrictions tab, under Allowed sizes, click to select the Only messages less than (KB) check box, and then type the size (in KB) that you want to permit.

SMTP virtual server setting

This setting determines the maximum size of a message that is permitted to pass through a virtual server.
To configure the Simple Mail Transfer Protocol (SMTP) virtual server setting, follow these steps:
   

• Goto Start -> Programs -> Microsoft Exchange -> System Manager.
• Expand Administrative Groups, and then expand Your Administrative Group Name, where Your Administrative Group Name is the name of your administrative group.
• Expand Servers, and then expand Your Server Name, where Your Server Name is the name of your server.
• Expand Protocols, and then expand the SMTP node.
• Right-click SMTP Virtual Server Name, where SMTP Virtual Server Name is the name of your SMTP virtual server, and then click Properties.
• Click the Messages tab to set the maximum size that you want to permit.

User mailbox setting

This setting determines the maximum size of a message that users can send or receive through their mailboxes. The information store prevents an oversized message from being sent to Transport if the message size exceeds the user mailbox maximum message size setting.
To configure an individual user's mailbox settings, follow these steps:
   

• Start the Active Directory Users and Computers snap-in, and then locate the user account that you want to configure.
• Right-click the user's account, and then click Properties.
• Click the Exchange General tab, and then click Delivery Restrictions to set the maximum size that you want to permit.

Example for setting size limit:
Consider an example with below values:
    >The global setting is set to 5 MB.
    >The Exchange SMTP connector is set to 3 MB.
    >The SMTP virtual server is set to 4 MB.
    >The user mailbox setting is set to 2 MB.
    With these settings users can send and receive messages that are a maximum of 5 MB. Users can send messages through the connector that are a maximum of 3 MB. All mail that passes through the SMTP Virtual Server (sending or receiving) is limited to 4MB. The individual user, whose mailbox setting is 2 MB, is also limited to sending and receiving messages that are a maximum of 2 MB.