Even in a properly functioning Exchange 2003 SMTP queue, corrupt messages can become stuck and cause mail flow issues. Performance Monitor (Perfmon) is a tool within Exchange Server Setup that can be configured to alert administrators when any SMTP queues in an Exchange 2003 environment reach a designated threshold. By monitoring the server for corrupt messages or denial-of-service attacks, administrators can circumvent SMTP message queue problems and email delivery failures. This tip by Exchange MVP Brien Posey explains how.
If Exchange Server 2003 SMTP queues are working properly, corrupt messages occasionally may become stuck in a queue. This can cause the queue to fill up and prevent mail flow until the damaged messages are removed. The process of removing damaged email from an SMTP queue is simple; however, Exchange Server doesn't alert administrators when a message becomes stuck. Typically, delivery of user email simply stops.
Microsoft and other third-party vendors offer solutions that detect message queue back-up failures. Such applications tend to be expensive and beyond the scope of small or medium-sized enterprises (SMBs). An alternative is to configure the Performance Monitor to alert you of message queue problems.
When Exchange Server is initially deployed, the Setup program installs various Exchange-specific Performance Monitor objects. Similar to the default counters in Microsoft Windows, these counters enable you to measure different aspects of Exchange Server performance.
The Send Queue Size counter monitors Exchange Server message queues. This tool is located within the MSExchangeIS Mailbox performance object. But before you can configure the server to detect message queue problems, you must monitor this counter to determine the maximum number of messages per queue under normal circumstances. Watch this counter during periods of peak usage. Additionally, this counter is storage group-specific, so you will have a separate instance of the counter for each storage group.
Once you've determined average queue length, you decide what value might indicate queue problems. For example, if there are 20 messages in the queue every Monday at 8 a.m ., you might conclude that 40 messages in the queue would indicate a problem. Whatever value you decide on, be sure to leave some room for unexpected usage spikes and future business growth.
Once you've determined a threshold value, configure the Performance Monitor to trigger an alert if values exceeded this level:
- Enter the Perform command at the Run prompt to open the Performance Monitor console.
- Navigate through the console tree to Performance Logs and Alerts -> Alerts.
- Right click on the Alerts container and choose New Alert Settings from the menu.
- When prompted for a name for the new alert, enter Send Queue Alert.
- Enter the words Alert if 40 Messages into the Comment field of the properties sheet and click Add (Figure 1).
Figure 1. Set the threshold value of messages in the queue using the Performance Monitor console.
- On the following screen, choose the MSExchangeIS Mailbox performance object.
- Select the Send Queue Size counter.
- Select the storage group that you want to monitor, as shown in Figure 2.
Figure 2. Configure the MSExchangeIS Mailbox/Send Queue Size counter to monitor a certain storage group.
- Click Add.
- Click Close.
- Set the following dialog box to send an alert when a value is over the set threshold value (Figure 3).
Figure 3. Configure Windows to send an alert when the counter's value is over 40.
Now you should set the sample interval to a higher threshold number to minimize the affect that monitoring has on the server's performance.
- Select the Action tab.
- Select the Send A Network Message To checkbox.
- Enter your username in the space provided (Figure 4).
Figure 4. Configure Windows to send a message when queues exceed set threshold values.
- Click OK.
- Right click on the new alert within the Alerts container and confirm that it has started.
About the author: Brien M. Posey, MCSE, is a four-time recipient of Microsoft's Most Valuable Professional Award for his work with Windows Server, Internet Information Server (IIS) and Exchange Server. Brien has served as CIO for a nationwide chain of hospitals and healthcare facilities, and was once a network administrator for Fort Knox. You can visit Brien's personal Web site at www.brienposey.com.
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