Managing Queues

You usually won't see messages in queues because they're processed and routed quickly. Messages come into a queue, Exchange Server performs a lookup or establishes a connection, and then Exchange Server either moves the message to a new queue or delivers it to its destination.

Understanding Queue Summaries and Queue States

Messages remain in a queue when there's a problem. To check for problem messages, use the Queue Viewer to examine the number of messages in the queues. If you see a queue with a consistent or growing number of messages, there might be a problem. Again, normally, messages should come into a queue and then be processed fairly quickly. Because of this, the number of messages in a queue should gradually decrease over time as the messages are processed, providing no new messages come into the queue.

Whenever you click the Queues tab in Queue Viewer, you get a summary of the currently available queues for the selected server. Although queue summaries provide important details for troubleshooting message flow problems, you do have to know what to look for. The connection status is the key information to look at first. This value tells you the state of the queue. States you'll see include these:

• Ready A ready queue is needed to allow messages to be transported. When queues are ready, they can have a connection allocated to them.

• Retry A connection attempt has failed, and the server is waiting to retry.

• Scheduled The server is waiting for a scheduled connection time.

• Remote The server is waiting for a remote dequeue command (TURN/ETRN).

• Suspended The queue is suspended, and none of its messages can be processed for routing. Messages can enter the queue, however, as long as the Exchange routing Categorizer is running. You must resume the queue to resume normal queue operations.

Administrators can choose to enable or disable connections to queues by suspending them. If a queue is suspended, it is unable to route and deliver messages.

You can change the queue state to Ready by clicking the Resume command. When you do this, Exchange Server should immediately enable the queue, which allows messages to be routed and delivered from it. If a queue is in the retry state, you can force an immediate retry using the Retry command.

Other summary information that you might find useful in troubleshooting includes:

• Next Hop Domain Tells you the type of the queue, such as whether it is a submission queue or an unreachable queue. For mailbox delivery and remote delivery queues, this field tells you the next hop domain. Messages queued for delivery to an EdgeSync server list the associated site and destination, such as EdgeSync – Default-First-Site Name To Internet.

• Message Count Tells you the total number of messages waiting in the queue. If you see a large number, you could have a connectivity or routing problem.

• Next Retry Time When the connection state is Retry, this column tells you when another connection attempt will be made. You can click the Retry command to attempt a connection immediately.

• Last Retry Time When the connection state is Retry, this column tells you when the last retry attempt was made.

• Last Error Tells you the error code and details of the last error to occur in a particular queue. This can help you determine why a queue is having delivery problems.

Refreshing the Queue View

Use the queue summaries and queue state information to help you find queuing problems, as discussed in the earlier section of this chapter entitled, "Understanding Queue Summaries and Queue States." By default, the queue view is refreshed every 30 seconds, and the maximum number of message items that can be listed on each page is 1,000.

To change the viewing options, follow these steps:

1. In Queue Viewer, on the View menu, click Options.

2. To turn off automatic refresh, clear the Auto-Refresh Screen check box. Otherwise, enable automatic refresh by selecting the Auto-Refresh Screen check box.

3. In the Refresh Interval text box, type a specific refresh rate in seconds.

4. Type the desired maximum number of messaging items to be displayed per page in the Number Of Items To Display text box. Click OK.

Working with Messages in Queues

To manage queues, you must enumerate messages. This process allows you to examine queue contents and perform management tasks on messages within a particular queue.

The easiest way to enumerate messages is to do so in sets of 1,000. To display the first 1,000 messages in a queue, follow these steps:

1. On the Queues tab in Queue Viewer, you should see a list of available queues. Double-click a queue to enumerate the first 1,000 messages, as shown in Figure 17-10

   
   Figure 17-10: The Queue Viewer provides a summary for each message in a queue.

2. After you enumerate messages in a queue, you can examine message details by double-clicking the entries for individual messages.

You can also create a filter to search for specific types of messages. To do this, follow these steps:

1. Double-click the queue with which you want to work. This enumerates the first 1,000 messages in the queue, as discussed previously.

2. If you haven't previously created a filter, click Create Filter.

3. Use the first selection list to specify the field you want to use for filtering messages. You can filter messages by: Date Received, Expiration Time, From Address, Internet Message ID, Last Error, Message Source Name, Queue ID, SCL, Size (KB), Source IP, Status, and Subject.

4. Use the second selection list to specify the filter criteria. The available filter criteria depend on the filter field and include: Equals, Does Not Equal, Contains, Does Not Contain, Greater Than, and Less Than.

5. Use the text box provided to specify the exact criteria to match. For example, if you are filtering messages using the Status field, you may want to see all messages where the Status field equals Retry. Your filter is automatically applied, and you can examine message details by double-clicking the entries for individual messages.

6. To stop filtering, click the Remove Filter button.

Forcing Connections to Queues

In many cases, you can change the queue state to Ready by forcing a connection. Simply right-click the queue, and then select Retry. When you do this, Exchange Server should immediately enable connections to the queue, and this should allow messages to be routed to and delivered from it.

Suspending and Resuming Queues

When you suspend a queue, all message transfer out of that queue stops. This means that messages can continue to enter the queue, but no messages will leave it. To restore normal operations, you must resume the queue.

You suspend and resume a queue by completing the following steps:

1. On the Queues tab in Queue Viewer, you should see a list of available queues. Right-click a queue, and then select Suspend.

2. When you're done troubleshooting, right-click the queue, and then select Resume.

Another way to suspend messages in a queue is to do so selectively. In this way, you can control the transport of a single message or several messages that might be causing problems on the server. For example, if a large message is delaying the delivery of other messages, you can suspend that message until other messages have left the queue. Afterward, you can resume the message to resume normal delivery.

To suspend and then resume individual messages, complete the following steps:

1. On the Queues tab in Queue Viewer, you should see a list of available queues. Double-click the queue with which you want to work.

2. Right-click the problem message, and then select Suspend. You can select multiple messages using Shift and Ctrl.

3. When you're ready to resume delivery of the message, right-click the problem message, and then select Resume.

Deleting Messages from Queues

You can remove messages from queues, if necessary. To do this, follow these steps:

1. On the Queues tab in Queue Viewer, you should see a list of available queues. Double-click the queue with which you want to work.

2. Right-click the problem message. You can select multiple messages using Shift and Ctrl, and then right-click. Select one of the following options from the shortcut menu:

   • q Remove (With NDR) Deletes the selected messages from the queue and notifies the sender with a nondelivery report (NDR)

   • q Remove (Without Sending NDR) Deletes the message(s) from the queue without sending an NDR to the sender

3. When prompted, click Yes to confirm the deletion.

Deleting messages from a queue removes them from the messaging system permanently. You can't recover the deleted messages.