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Non-Cached Exchange Mode Performance?

  • Can someone shed some light on running Outlook 2010 in Non-Cached Exchange mode with Office 365 / Exchange Online? Mainly regarding its Best Practices, if it is supported with Office 365 / Exchange Online, and bandwidth requirements.

    We recently migrated our organization from a Hosted Exchange 2007 provider to Office 365. After performing the cutover, we started to notice that Outlook was failing to fully update various users Inbox folders (would sit there saying "Updating Inbox (1.99GB)", and would never complete). Because Outlook was failing to update the Inbox folder, any new messages sent to that user after they opened Outlook would not appear in Outlook - but they would appear in OWA and on their mobile device. This doesn't appear to be an OST corruption issue; it is spread across multiple users/mailboxes, and when I attempt to recreate their mail profile / OST on their workstation, the issue still arrises. 

    When I opened a support ticket with Microsoft Online Services support, they advised me to switch the affected users to Non-Cached Exchange mode. I haven't switched all our users to this (currently testing it with 5-10 users), but I already have bandwidth/speed concerns. 

    So hopefully someone can shed some light on Non-Cached Exchange Mode - because I was originally advised to only run mailboxes in Cached Exchange Mode with Office 365. 

  • Hi brgnewman,

    Since you mentioned that you have contacted Microsoft Support, I understand you have submitted a service request to fix the issue. Could you provide the service request number for me? Therefore I would help to check if the issue has been fixed by our support engineers or not.

    Since this is your privacy, I will send private message to you to request the SR number. Therefore, I can help you check the SR status.

    To access the private message:

    1.Please go to the Your details section on the right side of the community site.

    2.Click Private messages.

    3.Click the subject title of the response to read the message.

    Linda Wang

  • Hi brgnewman,

    Thanks for your reply about the Service Request number.

    I have checked the service request status and found that our SR engineers are working to help you research and troubleshoot this issue.

    If this is any update or solution about it, I will also help to post the solution here.

    I will keep monitoring the service request.

    Linda Wang

  • Hi brgnewman,

                                          I'm having the same issue. Could you please let me know the solution when it is resolved?

  • Ckar,

    This issue is still ongoing for our organization - you may want to check out for an ongoing conversation regarding this issue.

    I was advised by the Technical Support Engineer today to try and enable Cached Mode again - however, after 20 minutes my Inbox became stuck at 2.1GB remaining.

    If I hear anything else, I will update this topic.



  • Hi ckar, brgnewman,

    Thanks for your update.

    I am also monitoring the service request now and I find that MS support engineers are still working on it. When the issue is resolved, I will post the causes and solution here for you and other users who also encounters the same issue to refer to.

    Linda Wang

  • Anyone have any updates regarding this issue?

    I have an office full of employees questioning Microsoft's ability to support their own products and services, and as well my ability to be an administrator. If I run Outlook in Cached Exchange Mode, Inbox folders never finish downloading/synchronizing. If I run Outlook in Non-Cached Exchange Mode, users complain about performance and delays.

    This needs to be resolved ASAP - my users are getting restless and losing their patience both with Microsoft and myself.

  • Hi Folks,

    Check this thread for a solution on how to get cached mode working correctly:

  • Brendan - Where is this solution/workaround you speak of? All I see is further complaints regarding this issue...

  • FYI:

    "Incident EX2355 - Aug 15, 2012 11:22 PM: We are continuing to investigate mitigation for an issue where a small number of users are having a problem with the first sync of their mailbox when using Outlook in cached mode. If the mailbox size is greater than 1G, time-out errors can occur. To work around this issue, users should use Outlook in online mode during the initial sync. Outlook Web App is unaffected and only new users may see this error. We will provide an update when we have more information. We apologize for this inconvenience and thank you for your patience while we resolve this service issue."

  • I have just read this incident and tried to read the post-incident report, but it has been taken down. I can confirm that my company is now experiencing this issue. What I am seeing at times are emails disappearing in some folders with cached Exchange mode on, then turning it off will make those emails reappear, then emails in other folders disappear. All folders look fine in OWA. Is there a solution I am not seeing?

  • Hi Jimmy,

    I would like to explain that the same issue may be caused by different reason in result of different actions and environments.

    Therefore, in order to provide you with more efficient support, it is recommended you post a new thread in our forum. One of our support engineers will focus on the issue you encountered.

    Allen Zhang