If you get this message it means that your server is busy and there are not enough free threads (or connections) to process further requests. No more transactions can be processed until the existing transactions complete and free up some of the threads.
There can be a number of reasons for your system running out of threads.
- You may simply have a server that is too busy for the number of threads you have set. For example, you may have more users trying to use the system than threads available. To alleviate this problem you can increase the number of threads the server uses. You set the number of threads under Incoming > Threads.
- Your system may be under attack from an external source. In this case you can see in the logs where these connections are coming from and ban them from connecting at all under GMS Anti-spam > Connect > Banned Hosts. You can also limit the number of connections from a remote IP address to any of your services under the Mail > Security > Sessions page.
- You may be using VSM (formerly supplied by Gordano) to provide virus scanning services. The VSM module provides single threaded virus scanning, i.e. only one message can be scanned at any one time. If you have a busy server then any further messages that need to be scanned will queue up waiting for their turn to talk to the scanner. This will obviously cause a backup and hence threads to be held in use for longer periods of time.
If this is the case then you should look at upgrading to GMS Anti-Virus which provides high speed multi threaded virus scanning. GMS Anti-Virus is tightly integrated into GMS and has an almost imperceptible effect on the operation of the server.
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