Jan 24, 2014 at 2:05 PM
While doing some high volume restores via MAPI at times some items cannot be restored or folders cannot be created. its not rights related because if we wait until we are not pushing as much data and then go back and do same action it works just fine, i.e. no error.

The network itself has a tremendous amount of bandwidth so that is not the issue.

Additionally the source and destination machines are fine in terms of resources, i.e. CPU, MEMORY etc so in short there are no resource constraints.

So it got me to wondering if there was any type of MAPI Saturation point and if so can that be measured so that we can determine best course, i.e. oh snap look we are at 95% MAPI saturation so take action xyz.


Jan 24, 2014 at 2:18 PM
Your scenario is somewhat vague so it's difficult to guess. You might be talking about MAPI connecting to an Exchange server. The Exchange server you might be talking about might be throttling your connection if you're hammering the server. You can turn on throttling logging here:

And if you are being throttled, you can look at these throttling policies:

You can also look at building your client so as not to hammer the server so hard, such as ensuring you close items after you open them, or using the contents table to get information about items instead of opening the item to get it - stuff like that.

Next time, you might want to be more specific about your scenario. Also, if you're getting errors, say what they are.
Jan 24, 2014 at 2:43 PM
Thanks for the quick reply and;
  1. Yes correct its communication with Exchange during restore of items.
  2. No its not a server throttling issue and we already have a policy that removes all limits
  3. The server is also not overwhelmed, i.e. no resources are constrained from source to path
  4. I am not the developer on this, but will have one of my team members post back with additional information regarding the issue in short order. We have looked at this pretty thoroughly in terms of possible causes, i.e. network saturation, resource constraints for source and target machines and there is absolutely no issues there. That lead me to wonder if all other resources are not constrained can MAPI itself can get overloaded/saturated?
Stand by and I will get some more technical info regarding the errors we are seeing
Jan 24, 2014 at 2:48 PM
Do you know it's not throttling because you've turned on throttle logging and confirmed that there is no throttling being logged or because you've configured a policy and you're trusting that the policy is working to exempt you from throttling? If you haven't checked the logging, you need to.
Jan 24, 2014 at 2:54 PM
Good question and;
  1. We are relying on the fact that throttling is setup properly and the profile being used is assigned to the throttling policy.
  2. My team may have already checked that, however I should personally look at this to be 100% sure. Where would we check to ensure no throttling is being imposed?
  3. We are able to make this happen regardless of Exchange version i.e. 2003, 2007, 2010 and 2013. For 2010 and 2013 the throttling is being used. For 2007 since we cannot assign a policy to a user, we just turned throttling off on the server side and still the same issue
Jan 25, 2014 at 5:28 PM
We are actually working with MAPI in several threads at one time, and an error in one thread leads to a waterfall of errors in the others.

In common when first error happens when we are trying to establish connection IMAPISession::OpenMsgStore() call that returns us Mailbox instance, that attempt fails and we get a bunch of errors with creating items and folders. Errors on item and folder levels almost always might be overcome by redoing the problem operation, I mean to do a few more attempts helps. The odd thing is we can be operating just fine and then all of the sudden we will see 20-30 errors in 1-2 seconds and then hours can pass before we get another instance.

  • MAPI error: not logged
    Low level MAPI error: 1142
    Message from MAPI: The attempt to log on to Microsoft Exchange has failed.
  • MAPI error: not logged
    Low level MAPI error: MAPI_E_NETWORK_ERROR
    Message from MAPI: Microsoft Exchange is not available. Either there are network problems or the Exchange server is down for maintenance.
    Low level MAPI error: 0x80040115
    Message from MAPI: Network problems are preventing connection to Microsoft Exchange.
    Low level MAPI error: 0x80070005
    Message from MAPI: You do not have sufficient permission to perform this operation on this object. See the folder contact or your system administrator.