SUMMARY
This step-by-step article describes how to manage messages. You can perform the following tasks to maximize message performance:
- Set connection limits.
- Set limits for both the message size and the number of recipients.
- Manage undeliverable messages.
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How to Limit the Number of Messages for Each Connection
You can limit the number of messages that are sent in a single connection. If you use multiple connections to deliver messages to a remote domain, you can improve system performance. After the set limit is reached, a new connection is automatically opened and the transmission continues until all of the messages are delivered.
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How to Determine the "Limit Number of Messages per Connection to" Setting
The
Limit number of messages per connection to setting affects only outgoing messages. You can use this setting to increase your server output speed; however, this speed has no effect on the rate that other servers process incoming messages. To determine the value for this setting, use Performance Monitor to view the
Messages Sent/sec counter for the Simple Mail Transfer Protocol (SMTP) Server object. The value of the
Limit number of messages per connection to setting should be less than the value that is indicated by the
Messages Sent/sec counter. If the
Messages Sent/sec counter value is
30, and you set your maximum connections to
50, simultaneous connections are not opened because the server cannot exceed 30 messages each second. Messages are sent as if they are sent in one long stream over one connection.
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How to Limit the Number of Messages That Are Sent in One Connection
- Start Microsoft Management Console (MMC), click SMTP virtual server, and then click Properties on the Action menu.
- Click the Messages tab, and then type a value in the Limit number of messages per connection to box.
NOTE: The default value is 20. The maximum value is 2,000,000,000.
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How to Set Message Size Limits
The
Limit session size to setting determines the maximum amount of data that is accepted during the total connection. This setting is the sum of all of the messages that are sent during the connection (this value applies only to the message body).
To set the message limit for the virtual server:
- Start MMC, click SMTP virtual server, and then click Properties on the Action menu.
- Type a value (in kilobytes [KB]) for the maximum size that you want to allow a message in the Limit message size to (KB) box.
NOTE: The default value is 2,048 KB and the minimum value is 1 KB. - Type a value to indicate the maximum total size of all of the messages in a given connection in the Limit session size to (KB) box.
Type a value that is larger than the maximum message size. Set this number carefully because the connecting message transfer agent (MTA) may submit the message repeatedly. The default size is 10,240 KB. Use a value that is greater than or equal to the value that you use for the Limit message size to setting.
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How to Set Recipient Limits
To set the maximum number of recipients for a single message that is sent in one connection:
- Start MMC, click SMTP virtual server, and then click Properties on the Action menu.
- Click the Messages tab, and then type a value in the Limit number of recipients per message to box.
NOTE: The default value is 100. If you do not want to set a limit, clear the Limit number of recipients per message to box.
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How to Store NDRs
If a message is undeliverable, Microsoft SMTP Service returns both the message and a non-delivery report (NDR) to the sender. You can configure the message settings so that copies of the NDR are sent to a location of your choice.
All NDRs use the same delivery process as other messages, including messages in which you attempt to resend the original message.
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How to Set a Storage Location for NDRs
- Start MMC, click SMTP virtual server, and then click Properties on the Action menu.
- Click the Messages tab, and then type the e-mail address of the mailbox that you want to use to store copies of the NDRs in the Send copy of Non-Delivery report to box.
Type any valid SMTP e-mail address. To disable this feature, clear the Send copy of Non-Delivery report to box. - Type the name of the folder that you want to use to store undeliverable messages in the Badmail directory box.
The default location is Drive:\Inetpub\Mailroot\Badmail. Click Browse to select another folder. You can designate a different folder; however, you must use a folder that is located on the same computer as Microsoft SMTP Service.
NOTE: Messages that are placed in the Badmail folder cannot be delivered or returned.
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