CASproc.exe (V2.6) instances can lock up when receiving email [RESOLVED as bug]

Does not happen at same time as other bugs I have reported so possibly not related to any of them.

When Outlook is receiving email, CAS spawns multiple CASproc.exe processes in the context of Outlook. These are normally unloaded when send receive completes. Sometimes Outlook fails to download the email, and the CASproc.exe processes seem to remain after send receive completes, even if send receive is cancelled. It may be that Outlook fails to send receive because the casproc.exe are locked - certainly the normal Outlook 'cannot contact server messages are not received. The problem then seems to become cumulative, with more CASproc.exe processes locking on each send receive. Fully closing and opening Outlook seems to resolve it. No evidence of lost emails thankfully.

Uninstall CAS & CSE & all is well - except occasional normal ‘server timeout’ messages. Disable CAS & all is well. Re-enable CAS problem starts again almost immediately. So it seems CAS (or possibly CSE) specific - will update if any experience to the contrary.

Using CAS with CSE, CMF, Ivault, and CIS. Also Avira, but free version without email scanning. Have tried disabling all Outlook plugins apart from CSE. Running Windows XP SP3 (32 bit). No other receive enabled mail software running (but several send enabled system management apps).

I have large whitelists for all 6-8 email accounts, which may explain why this is happening in my case.

Hope this helps


Hi Mouse:

      Each receiving on one account will spawn one CASProc.exe process.  This process will do some backgroud jobs for Challenge/Response policy. 
     For POP only supports one session for one accunt at a time, and CASProc.exe will hold one session for downloading emails from remote servers, mail clients may fail to set up one new session for the same account, that's why you get the 'server timeout message. This happens when you doing receiving frequently.

Thanks for the detailed reply, much appreciated.

I can see that the email client might not set up new CASproc instances, if the previous ones (communicating with the same account) have not terminated. I guess this depdends on the relationship between the server timeout set in the email client, and the frequency of download. Frequency of download is high in my case.

But what appears to be happening is more than this. The CASproc.exe seem to get locked, so that the email client cannot any longer communicate through them to the email server - I say seem becuase I’ve no way of monitoring this apart from sysinternals proccess explorer, which shows that the processes persist but do not seem to consume more than the occasional processor cycle, sometime none at all. The result - which of course I can observe - is that over several download cycles less and less accounts are downloading, until none do, unless the email client is re-started. The issue with the server timout messages is really that despite the fact that downloads are not occurring, I am NOT getting them - I’d expect that if the CASproc could not communiacte with the server, due to server load or maintenance, I would get the normal client server timeout error. When these proccesses get ‘locked’ (or I presume they are locked, cos they are not cosuming many cycles) I don’t get the timeout messages.

So a bit puzzling really. A bit undesirable too I guess as you’d want your software to deal with frequent email downloads? What do you think?

If I have time I’ll try experimenting with rates of download & Outlook server timeouts. I’m downloading around once per minute if you want to try and replicate. Of course this could be realted to my large whitelists in which case you may not be a able to replicate!

Best wishes


Just a little further info on this. The TCPIP connection which carries the POP3 connection from outlook appears to hang in the CLOSE_WAIT state when Outlook downloads get locked.

Contrary to previous information, a longer period of testing shows the problem can sometimes happen with CAS disabled - Outlook then does not launch CASproc, but email downloads can still lock with no error message. The problem clears completely if BOTH CSE and CAS are uninstalled (no other changes).


I am experiencing the exact same problem using Windows Live Mail. I am getting no error messages just the CASproc.exe (V2.6) getting stuck in the task bar and not closing. The normal processing continues, but the “stuck” CASproc.exe stays put unless I right click to close.

I am using Windows XP SP3 with a DSL connection as well.

Overall I am quite satisfied. But the hanging CASproc.exe gets rather frustrating. Hoping there is a solution.


I think I have just made this happen by pressing send receive in Oullook 2003 two times quickly in sucession, the second time before the first CASproc was closed by Outlook. I believe that the first CASproc was processing an email into quarantine at the time the second send-receive was initiatied. Result - an additional process was created and closed, but the original CASproc was never closed. The non-closed CASproc (presumably with the email stuck in it, as it never makes it into quarantine) recurs after the machine is rebooted. Hopefully this will help you to replicate this fault.

Oh should add that only reinstallation resolves this to my knowledge. Though I guess deleting the .qdb file and disabling and re-enabling the account might.

Best wishes


Have now discovered that this problem also happens also when the number of handles used by Outlook (due to the resource leakgae problem reported elsewhere) is very large eg 12,600!


Hi All:

   This problem is resolved in new CAS(2.7, now in Beta). 
   Your discussion is helpful for this product. Thanks!

Improved, for which many thanks. But still occurs sufficiently frequently to be a problem.

Please see Beta Corner/2.7 bug reports.

Best wishes