This article applies as of PRTG 22
What are the different kinds of Exchange transport queues and what are they used for?
Types of transport queues in Microsoft Exchange
PRTG comes with two sensors for monitoring Exchange queues:
Both can monitor various values of an Exchange queue, such as the length of specific queues.
A queue can be defined as a temporary holding location for messages that are waiting to enter the next step of processing, or as the number of messages with the same status. Different server roles determine on which systems the messages are queued:
- The Edge Transport role for messages coming from and going to the internet.
- The Hub Transport role for messages within the Exchange organization.
The routing of a message determines the type of queue in which a message is stored. In Exchange, there are five types of queues with different kinds of messages:
| Queue | Description |
|---|---|
| Submission Queue | Messages that must be resolved, routed, and processed by transport agents. |
| Mailbox Delivery Queue | Messages that are delivered to a mailbox server via encrypted Exchange RPC. |
| Remote Delivery Queue | Messages that are delivered to a remote server via SMTP. |
| Poison Message Queue | Isolated messages that are considered to be harmful to the Exchange system after a server failure and that are typically empty. Messages in this queue are suspended by default. |
| Unreachable Queue | Messages that cannot be routed to their destinations. |
The Exchange Mail Queue (PowerShell) sensor shows the additional channel Retrying Mails. This channel shows messages that could not be successfully delivered but make connection attempts with the destination domain.
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Disclaimer:
The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.
