Get to Know Brief About Outlook Cached Mode and OST File Size Management
Being an Exchange administrator, an individual tends to focus on the server, data centers, and networks. All that is important but, it is also important to be known by the fact that users imagine email system as the client experience. In other words, the admin needs to think of other real scenarios, as well as – is Outlook app performance stable or not, is it executing in an expected way? There are several factors, which influences the Microsoft Outlook performance. One such is caching. This blog is going to brief readers with Outlook cached mode and OST file along with their management approaches.
Introduction About Cached Mode
When a connection is established in between MS Outlook and Exchange account, the respective email client downloads replica of mailbox information to local cache. This is termed as “cached mode in Outlook”. There are two major benefits of Microsoft Outlook cached mode, which are described below :
Improves Performance – The performance of Microsoft Outlook in online mode is not proper. Earlier, when the application was connected with the Exchange servers that were around the end user, this online mode was quite good. Nowadays, mailboxes of Exchange are hosted upon the centralized datacenter’s servers or on Office 365 cloud. End users are establishing their mailboxes over a long distance. They are using Microsoft Outlook over a slow network like the home internet or public WiFi.
Work in Offline Mode – The second advantage of using Outlook cached mode email client is that it permits PC users to work with mailboxes in an offline connection. In absence of the internet connectivity, a person can compose and read emails in MS Outlook desktop application. When the connection gets re-established, automatic exchange of information takes place.
About Outlook Offline Storage Files
The local cache of Microsoft Outlook mailbox content is archived in OST or offline storage table file format. Depending on the edition of Outlook, the maximum OST file size is enlisted below:
- Outlook 2010, 2013, and 2016 – Maximum size of OST file is 50 GB
- Outlook 2007, 2003, and below – 20GB is the maximum size of OST file
The latest version of MS Outlook application supports UNICODE file format, which is also termed as the Large format. ANSI OST file structure used to be supported in the older edition of Outlook. In recent days, the email client uses UNICODE file format by default. The OST file size becomes a problem when it is about dealing with large-size mailboxes in Exchange on-premises and Exchange Online. Think of a question that ‘is it possible for OST file to hold entire content in the 100GB mailbox?’ The answer to this is No, it is not at all possible! However, if the maximum file size exceeds, users will be experiencing different problems. Corruption in OST file, unable to compose new Outlook mail, Microsoft Outlook gets hang, etc., issues exist in such situation.
There are high changes in OST files being getting corrupted. It means that to recover corrupt OST file, the file needs to be deleted and then, permit MS Outlook to re-download the mailboxes in a new OST file. This step consumes lots of time duration when there are a large number of mailboxes to be downloaded. It may also take two-three days in performing a complete rebuilding process.
Microsoft Launches Outlook 2016 / 2013 Cache Slider to Manage Outlook Cached Mode
Microsoft launched a method of partial mailboxes caching to handle with the huge mailbox quotas for the Exchange Online mailboxes. A cached mode slider was introduced with the release of MS Outlook 2013 edition, which is sometimes is also known as OST slider. Caching of an Outlook mailbox was nothing or all proposition, before the arrival of this feature. Outlook cached mode OST slider enables users to control the amount of mailbox information that is to be cached on your system hard disk.
Go to File >> Account Settings in Microsoft Outlook 2016 / 2013 and highlight the account. Click on Change to view the OST slider. This slider is not directly responsible for controlling OST file size in GB. It permits operators to choose the data to be downloaded from the mailbox by age. Its default settings are dependent on the hard disk size of your system.
With help of the Group Policy, persons can configure Outlook 2016 / 2013 cache slider. A Group Policy administrative template needs to be downloaded from the internet. If this Group Policy is not available then, make use of registry configuration method. Use:
‘HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\xx.0\Outlook\Cached Mode’ registry key. At the current location, change xx.0 with an appropriate value that is dependent on the Outlook version you are using.
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
Generate the value of DWORD for SyncWindowSetting and mention a suitable value :
0 = All (whole mailbox)
1 = 1 email item’s months
3 = 3 email item’s months
6 = 6 email item’s months
12 = 1 year of email items
24 = 2 years of email items
36 = 3 years of email items (for Outlook 2016 only)
60 = 5 years of email items (for Outlook 2016 only)
An additional settings range is required for all users who are working with MS Outlook 2016. This can be applied through DWORD value of SyncWindowSettingDays
3=3 Days
7=7 Days
14=14 Days
Both the values of the registry should be configured simultaneously in case of Microsoft Outlook 2016. Make desired configuration settings on suitable registry value and locate 0 to other value. For example – For setting the slider to 3 days, configure SyncWindowSettingDays to 3 and SyncWindowSetting to 0.
Conclusion
The task of managing Outlook cache mode and OST file size is not considered an essential one in the list of administrator work. But, enterprises should enlist this operation to maintain the performance of Outlook. Default configurations are suitable in several cases but, there are some conditions that demand some kind of updating. To make life easier for customers, Microsoft launched Outlook cached mode slider in 2016 / 2013 edition. This provides guidance in dealing with the size of OST file and cache mode of Outlook app.
