Lync – Unable to save conversation history in Outlook

Hello All

Recently we were being notified of an issue where Lync stops saving conversation history for user into outlook folder. Now there could be many reason behind this but we’ll be focusing on one typical reason behind this behavior between Lync and Outlook.


  • Conversation history does not appear in the Conversation History folder within Outlook 2010 or OWA.
  • Issuing an “outlook.exe / resetfolders”, does open Outlook and around 10 messages from the conversation history from Lync is sync’d (and this is replicated up to OWA), but no further are moved.
  • Using Lync on OWA results in the same symptoms.

Before we deep dive into issue, we need to know that Many of the features offered within Lync 2010 have dependencies on connectivity to a Microsoft Exchange mailbox.  For example, the conversation environment feature leverages both Exchange Web Services (EWS) and MAPI to manage Conversation History items. Unlike previous versions of Lync, EWS is now the primary method used to provide Microsoft Exchange integration features for the Lync client.  MAPI will be used if EWS is unavailable, but only in a limited capacity. For more details, we encourage you to read resource kit chapter Understanding & Troubleshooting Exchange server integration

For those who want to check on EWS & MAPI on their own client, can hold CTRL + Right Click on the Lync icon on the tool tray and select “Configuration Information”.  That will give you a screen shot of the status and settings for your Lync client



  1. Now EWS information being covered, we checked that EWS status in client was OK. We parsed through IIS logs in CAS and also captured Fiddler from client for checking if there’s any issue with EWS integration but all came up clean.
  2. Next we dig into Lync 2010 client logs to see why the issue is happening. To know more about how to enable Lync logging on client and how to analyze log files please refer here.
  3. The Lync client stores the conversation history in a spooler located in %userprofile%\AppData\Local\Microsoft\Communicator\\History Spooler.   The files themselves have a .hist file extension.  Checking there I could see that there were many waiting to be sent to the exchange server for archiving. The clients configuration information reported EWS status OK in step 1 – at this point my mind was narrating “what the heck is going on !”
  4. Then I bumped into article written by office 365 folks around same issue and provided details on why it’s happening. Basically user had more than 1000 folders in his or her Outlook. If you look at EWS extract below, you’ll see there’s a policy which is restricting number of folders to be returned before error is thrown. To determine if user is having more than 1000 folders, you can use the VB macro created by MS (shared below) OR you can use below cmdlet on Exchange management shell:



Exchange management shell cmdlet: (Get-Mailbox <user name> | Get-MailboxFolderStatistics).Count

To download VB macro – VB Macro for Outlook

Workaround: But the blog didn’t provide any information about workaround. It ended with note that issue will be resolved with upcoming versions of Lync 2010 with no ETA and un-fortunately that answer is not acceptable by users in our environment :S. So based on extract above, we tweaked the EWS throttling policy on Exchange side to increase the number of folders to be returned before an error is thrown. To do same, we used below cmdlet and voila users started reporting that conversation history folder is now getting up to date

Set-ThrottlingPolicy -Identity <Policy Name> -EWSFindCountLimit 2000

You need to be careful with how much you increase this limit too as the EWS query call for searching more than 1000 items will stay in memory of your CAS server causing memory overhead for storing that many results at a given time. For details about syntax of Set-ThrottlingPolicy cmdlet, please refer here.

What is EWS Find Count Limit: The EWSFindCountLimit parameter specifies the maximum result size of FindItem or FindFolder calls that can exist in memory on the Client Access server at the same time for this user in this current process. If an attempt is made to find more items or folders than your policy limit allows, an error is returned.

Update (06/27/2014) – We’ve published another post regarding Lync and EWS integration issue. If above solution doesn’t meets your scenario, check out our post below:

Hopefully this helps you to resolve this issue in your environment if there’re certain users who’ve more than 1000 folders in their Outlook client or mailbox.

 In case any further details required in this direction. Please let us know.

February 25, 2013  Tags: , ,   Posted in: Exchange Server 2010, Exchange Server 2013, Lync 2013

5 Responses

  1. Jetstressed - September 12, 2013

    Very usefull… had this for a user in our environment too.

  2. steve lindsey - May 8, 2014

    I came across your post, & this seems to be 1 of the better detailed ones i have come across.

    however your situation & solution does not work for me. The user i am having a problem with was saving everything fine, up until 4/9 then it all stopped. I do see in his history folders all the convo’s but from some reason they are not bein sent to exchange…

    this is also on Lync 2013 & Exchange 2013.

  3. LazyAdmin - May 8, 2014

    Thanks Steve, You can post query in our questions & answers section.

    Also, have you ensured that folder count in user’s mailbox is lesser than EWSFindCountLimit within your environment? And if you check Lync configuration information EWS status is showing ok? Any additional troubleshooting which you might have already done please?

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