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Peter
Asked: 2021-01-20 02:53:39 +0800 CST

Outlook 2016 ignoring cache ost settings

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Under account settings Outlook2016.
One has the option mail to keep offline in the gui, to cache Email.

Problem: For unknown reasons it stays at 1 month or all time.
One should be able to alter the period by policy or registry:

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\xx.0\Outlook\Cached Mode  
 xx.0 =   
  Outlook 2016 is 16.0  
  Outlook 2013 is 15.0  
  Outlook 2010 is 14.0  
  Outlook 2007 is 12.0  
  Outlook 2003 is 11.0  
  
Create a DWORD value of SyncWindowSetting, and then set the desired value:  
0 = All (whole mailbox)  
1 = 1 month of email items  
3 = 3 months of email items  
6 = 6 months of email items  
12 = 1 year of email items  
24 = 2 years of email items  
36 = 3 years of email items (Outlook 2016 only)  
60 = 5 years of email items (Outlook 2016 only)

I even added the Dword value Enable and set it to 1.

I need to have syncWindowSetting to 12, to keep one year of email cached in the OST, however outlook seams to completely ignore these values, and sticks to one month only or all
Any ideas to get it working for only 1 year are welcome

a registry export of my outlook settings is below:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\Cached Mode]
"SyncWindowSetting"=dword:0000000c
"SyncWindowSettingDays"=dword:00000000
"Enable"=dword:00000001

However whatever i do inside outlook 2016 it stays at 1 month.
As for registry permissions, the user and system can read above entries.
how it looks in outlook 2016

outlook activesync outlook-2016

1 Answers

  1. Best Answer

    Except SyncWindowSetting, another DWORD key is also required to be added in registry:

    DWORD: SyncWindowSetting Value: 12

    DWORD: SyncWindowSettingDays Value: 0

    The following table records the corresponding values of the two keys(Update allows administrators to set additional default mail and calendar synchronization windows for new Exchange accounts in Outlook 2016):

    enter image description here

    My test result is for your reference: enter image description here

    enter image description here

    Edit: Based on my research, for Cached Exchange mode, we could use the above keys to modify the default sync days of emails, but there're no registry keys to modify the sync days of an ActiveSync account. The following link about registry keys which are used for modifying sync days is for your reference: Cached Exchange Mode Sync Settings & Exchange ActiveSync

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