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iPhone 8 email delays for users with large number of Calendar entries on Exchange 2016 on-prem RRS feed

  • Question

  • Hello Everyone,

    We have a user that has an iPhone 8 64GB and that recently started having issues with email coming down very slowly and when user tries to open the email it just has a spinning circle and it takes a very long time for the email to load. Sometimes several minutes. User is using a native iOS mail app since the mailbox is on-prem and not exchange online.

    User has 168Mb/s wi-fi connection at home which should be more than adequate for email.

    Their mailbox size is less then 7GB. They do not use a PC, just an iPad and an iPhone.

    They have about 5300+ contacts and about 14000 calendar entries, 19000 items in the Inbox and about 400 folders in the Inbox.

    We did all the standard troubleshooting on the phone, restarted the phone, closed/reopened the app. None of that fixed the issue. We did not re-enroll since that would start the re-sync which user is too frustrated to do. We did try this with users mailbox on another device and it didn't work.

    The only thing that does stand out to us is number of calendar entries which I have read Microsoft recommends no more than 5000. We have also set an unlimited Throttling Policy on Exchange.

    I'm looking for options here as our user is very frustrated so any help on what else we should look at would be greatly appreciated.

    Friday, October 9, 2020 5:38 PM

Answers

  • Hi Lucas,

    Thanks for your reply. We haven't changed anything prior to this issue occurring. I wanted to follow up and let you guys know that we have found what was causing the issue.

    User's Cloud Backup was corrupt for some reason, so every time we would restore their backup on a brand new device which was provisioned with the same Profiles and that Cloud backup, Outlook would just show spinning  circle and mail for that user would never download.

    Once we provisioned a brand new device, as new device, without restoring users backup, Outlook mail would work normally and all the mail would come down.

    All this was happening on range of iPhone and iPad Pro devices, from 13.7 to 14.0.1 IOS and iPadOS versions.

    Bottom line, corrupted backup...provisioned a device as new and worked fine.

    • Marked as answer by DenisNYC Wednesday, October 21, 2020 10:10 PM
    Wednesday, October 21, 2020 10:10 PM

All replies

  • Hi DenisNYC,

    Did you change any settings before this issue occurred?

    Do other users in the same Exchange organization have the same problem?
    According to the information you provided, I think it may be caused by too many calendar items in your mailbox. As you mentioned, according to the official Microsoft article, if there are more than 5000 items in the calendar folder, it may cause the performance of the mailbox problem appear.

    Please following the steps and see if the issue is resolved:

    1. Please try to download the “Outlook for IOS” app on iPhone and configure account, then see if the issue still occurred.

    2. Please try to remove your email account from iPhone and re-add it.

    3. Please try to move the user mailbox to another database.

    4. Please reset the network settings on iPhone/IPad.

    5. If possible, please reduce the number of calendar files and the size of mailbox storage files appropriately.

    In addition, incorrect firewall settings can also cause this problem. Please check whether the firewall has settings similar to filtering web content. Third-party anti-virus software may also cause this issue.

    Please note that, this Exchange Server Development forum mainly focuses on scripting issues, And the previous TechNet Exchange forum has been migrated to Q&A forum, please post your issues there if you need further support. 

    Regards,

    Lucas Liu


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Monday, October 12, 2020 8:17 AM
  • Hi Lucas,

    Thanks for your reply. We haven't changed anything prior to this issue occurring. I wanted to follow up and let you guys know that we have found what was causing the issue.

    User's Cloud Backup was corrupt for some reason, so every time we would restore their backup on a brand new device which was provisioned with the same Profiles and that Cloud backup, Outlook would just show spinning  circle and mail for that user would never download.

    Once we provisioned a brand new device, as new device, without restoring users backup, Outlook mail would work normally and all the mail would come down.

    All this was happening on range of iPhone and iPad Pro devices, from 13.7 to 14.0.1 IOS and iPadOS versions.

    Bottom line, corrupted backup...provisioned a device as new and worked fine.

    • Marked as answer by DenisNYC Wednesday, October 21, 2020 10:10 PM
    Wednesday, October 21, 2020 10:10 PM