[Users] June 23, 2020 Zeta Alliance Conference Call Summary

[Randy Leiker]

Hello Zeta Alliance Community, 

Here is a summary of this week’s conference call. A few brief reminders: 


    * Conference calls are every Tuesday and open to all using either the FreeConferenceCall.com VoIP app or via a dial-in number: [ https://www.freeconferencecall.com/wall/zetalliance | https://www.freeconferencecall.com/wall/zetalliance ] 
    * Each week’s call agenda can be found at: [ https://docs.google.com/document/d/1uUUDJpwp2CAylU6lxtbEdVcUX_qSbciyes6gLTWw2fY/edit | https://docs.google.com/document/d/1uUUDJpwp2CAylU6lxtbEdVcUX_qSbciyes6gLTWw2fY/edit ] 
    * A copy of each week’s summary is also posted to the Zimbra Forums: 
        * April 2020 : [ https://forums.zimbra.org/viewtopic.php?f=9&t=68073 | https://forums.zimbra.org/viewtopic.php?f=9&t=68073 ] 
        * May 2020 : [ https://forums.zimbra.org/viewtopic.php?f=9&t=68214 ] [ https://forums.zimbra.org/viewtopic.php?f=9&t=68214 | https://forums.zimbra.org/viewtopic.php?f=9&t=68214 ] 
        * June 2020 : [ https://forums.zimbra.org/viewtopic.php?f=9&t=68342 | https://forums.zimbra.org/viewtopic.php?f=9&t=68342 ] 
    * Constructive feedback on these call summaries is always welcome. 

June 23, 2020 Conference Call Summary 

ActiveSync Issue When Synchronizing A Large Number Of Folders 
Mark S. reported encountering an issue with one of his clients who has both Android and iPhones, which are setup to sync with Zimbra using ActiveSync, where the devices never finish syncing, and endlessly restart the sync process. He said this is occurring in 8.8.15 both prior to and after installing Patch 10. He explained that the affected clients’ devices are syncing mailboxes with large numbers of mailbox folders for email items up to 30 days old, with many of those folders also setup for sharing. The user devices do not report any errors when the sync process fails and restarts, but new email only appears in the Zimbra Web Client, and not on the users’ phones. Each time the sync process fails, most of the contacts and calendar items from the phones also disappear, but then slowly re-appear as each new sync attempt restarts. Mark said that checking the sync.log file on his Zimbra servers shows a warning similar to: “Mobile (username) sync invalid sync key for folder (folder number/ID)”. Mark said he opened a support case with Zimbra Support, and asked those on the call if they had encountered a similar issue with reaching an upper limit on the number of items that ActiveSync can successfully synchronize to a phone. 

Cine commented that he recalled a case where a Zimbra user had 158,000 mailbox folders in Outlook, and Outlook was unable to successfully complete a sync within the lifetime of the Zimbra auth token before the auth token expired. He said that 70% of ActiveSync issues tend to be related to issues with calendar items and suggested that if that is the cause of the issue that Mark described, that upgrading the client to ActiveSync version 16 might be the solution, since an estimated 80% of the code related to calendar synchronization was re-written in ActiveSync 16. Cine also suggested using a debug feature built-in to Zimbra ( [ https://docs.zextras.com/zextras-suite-documentation/latest/mobile-troubleshooting.html#_account_loggers_and_mobile_troubleshooting | https://docs.zextras.com/zextras-suite-documentation/latest/mobile-troubleshooting.html#_account_loggers_and_mobile_troubleshooting ] ) to determine the point at which errors begin occurring for a given phone during an ActiveSync session. Cine explained that each mailbox folder has a unique sync key assigned to it, and that from Mark’s description, he suspects that after an ActiveSync client (phone) or the Zimbra server reach a certain threshold of errors, it decides to reset the sync key back to 0, thereby resulting in another full re-sync of the phone being attempted. Mark asked if the cause of this issue might be related to multiple devices attempting an ActiveSync against the same folder. Cine said that that should not matter, as the sync keys are device-specific. John E. added that it could be related, as he recalled a case where the heartbeat interval setting may be non-negotiable and cause the phone not to sync at all as was found to be occurring with the Outlook for Android app. 

Restricting Subscribed IMAP Folders For the iPhone 
Noah P. asked if anyone knew of an IMAP email app, available for the iPhone, that could selectively subscribe to a subset of the email folders within a mailbox, as compared to the default behavior of subscribing to all IMAP folders within a mailbox. Cine suggested Nine (9folders.com), which costs $10. John E. suggested that the native iOS Mail app should be able to be configured to avoid subscribing to select folders, but this capability could not be confirmed during the call. 

Mobile Synchronization For Shared Folders 
Mark S. said that one of his clients has all of their shared folders currently enabled for syncing with mobile devices and asked how to disable syncing of these folders. Cine said that this is not the default behavior, as shared folders are normally disabled and must be individually enabled for syncing to mobile devices. Mark said he suspects the client might have enabled this setting for all shared folders prior to moving to his hosted Zimbra environment and expressed concern about needing to manually disable this feature for a large number of shared folders. Cine said this is fortunately easy to do and requires a simple three line Bash script to perform a mass update for the client’s shared folders. 


Randy Leiker ( randy at skywaynetworks.com ) 
Skyway Networks, LLC 

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