Use Cached Exchange Mode To Download Email To An Outlook Data File
Cynthia Figarsky
Cached Exchange Mode enables a better experience when you use an Exchange account. In this mode, a copy of your mailbox is saved on your computer. This copy provides quick access to your data, and it is frequently updated with the server that runs Microsoft Exchange.
When data is optimized for an Exchange connection type, the type of items that are synchronized with your server mailbox are different. For example, when you use a fast connection, Office Outlook 2007 copies the header, body, and attachments of an email item from the email server to your computer. When a slower connection is selected, only headers are automatically downloaded. The body and any associated attachments are downloaded only when requested by you, or as necessary for synchronization with personal digital assistants (PDAs), auto archiving, and some client-side rules. In a slower connection environment, the Offline Address Book is also not automatically updated. However, you do have the option of manually requesting the update.
Later that day, you use a modem for dial-up access to your Exchange account. Outlook recognizes your connection is slow and automatically optimizes for that connection by downloading only headers and not updating the Offline Address Book. Additional optimizations are also made to reduce the amount of data sent over the connection.
Cached Exchange mode is a feature in Microsoft Outlook that stores a copy of a user's Exchange mailbox on their computer. This mode enables the user to access their mailbox data locally from the offline data file (.ost) even when an Internet connection is not available.
In this mode, when users open a mailbox item, such as an email, contact, or calendar item, Outlook first checks the cache to see if the latest version of the mailbox item is available. If the latest version is available, Outlook displays it. If not, Outlook queries the Exchange server for the latest version of the item.
Cached Exchange mode also speeds up the opening of Outlook items and reduces server load, as it eliminates the need to repeatedly query the Exchange server for the same information. For instance, if Outlook 365 is not updating inbox automatically, the Cached Exchange mode helps to retrieve emails from the local OST file.
Cached Exchange mode is a mode in which a copy of your Exchange mailbox is stored on the local computer, enabling offline access to email, contacts, and calendar items. In this mode, changes made to items in the cache are automatically synchronized with the Exchange server the next time you connect to the email server.
The Online mode, on the other hand, is a mode in which all data is stored on the Exchange server and accessed by connecting directly to the server in real-time. You do not have offline access to your mailbox in this mode and must have an active Internet connection to access the mailbox data. The following table illustrates the difference between the two modes.
Disabling the cache mode frees up the disk space used to store the local copy of the Exchange mailbox, and changes made to items in the mailbox will be reflected in real-time. However, disabling the cache mode may result in slower performance and responsiveness in Outlook, as the application will no longer have a local copy of the mailbox data to work with. Additionally, if you have poor Internet connectivity, you may experience issues accessing your mailbox data.
Shared folders in Microsoft Outlook refer to folders that are shared by multiple users within an organization. These folders may include calendars, contacts, tasks, and other items, and they can be accessed and modified by authorized users. Outlook downloads these folders to the local cache when you enable the cached mode for shared folders. Follow the steps to enable cached mode for the shared folders and Public folder favorites.
Outlook uses Cached Exchange mode when setting up an Exchange or Office 365 account and stores a cached copy of your online mailbox data on your local computer. When you enable the Cached mode, Outlook creates a local OST file to store the mailbox items and syncs the cached file with the server once the internet connection is restored. However, when the Exchange server goes down or is inaccessible due to a system crash, the OST file becomes orphaned. In such cases, you must convert the OST to PST and import your mailbox items into Outlook to retrieve the inaccessible data. EdbMails is one such application that enables you to convert orphaned OST to PST files and import Outlook OST to Office 365 and Exchange.
Cached Exchange Mode gives users a seamless online and offline Outlook experience by caching the user's mailbox and the Offline Address Book (OAB) locally. With Cached Exchange Mode, which is the default setting for users, Outlook no longer depends on continuous network connectivity for access to user information. When a user is connected, Outlook continuously updates users' mailboxes so that the mailboxes are kept up to date. If a user disconnects from the network, for example, by moving to an area without Wi-Fi access, the user can continue to access the last available email data.
Delayed delivery options are client side in cached mode and server side in online mode. So, when you use Cached Exchange Mode, Outlook must be connected and open at the assigned delivery time for the delayed delivery message to be sent.
Whenever the user is offline and using Outlook 2016, the program works from this local copy and with the Offline Address Book (OAB). When the user is online, the cached mailbox and OAB are periodically updated from Exchange Server in the background. Any email messages the user drafted while offline are automatically sent when that user is back online.
The slider allows an Outlook 2016 user to limit the email messages that are locally synchronized in a Microsoft Outlook data file (.ost). By default, if Cached Exchange Mode is enabled, Outlook 2016 caches email messages only from the last 12 months and removes anything older from the local cache for the PC. These default settings depend on the device, with mobile devices having smaller default settings. The email messages that are removed from the local cache are still available for users to view, but they'll need to be connected to Exchange Server to view them. Users can view messages that were removed from the local cache by scrolling to the end of a message list in a folder and clicking the message Click here to view more on Microsoft Exchange. Users can also change how much email to keep offline. You, the administrator, can change the default age or enforce the age of email messages that are removed from the local cache.
(If you're an Office 365 subscriber with semi-annual updates, under Offline Settings, check Use Cached Exchange Mode to download email to an Outlook data file.
If a user is offline and using Outlook, the program works from this local copy and with the Offline Address Book (OAB). Any email messages the user drafted while offline are automatically sent when that user is back online. When the user is online, the cached mailbox and OAB are periodically updated from the Exchange Server in the background.
The second type of Exchange connection mode is Online Mode. Online Mode works by using information directly from the server; as the name implies, it requires a connection. Mailbox data is only cached in memory and never written to disk. You can enable Online Mode by disabling Cached Exchange Mode.
So I am a sole-proprietor and have used Outlook 365 Exchange for years with no problem. I am running Windows 11 (all updates) and just recently, Outlook would stop receiving or sending any email and would just sit there with the "requesting Data from Server" note in the message bar. When I test my ethernet network connection, (1 gb) both the download and upload speeds are excellent (in excess of 900 Mbps). I spent an hour and a half with my ISP (Verizon) diagnosing the system to see if there was anything on their side and the only thing they could come up with in all that time was to turn off cached mode.....at which point all my email immediately started to download (even when connected to the NIC). But I find not working in cached mode causes Outlook to "stutter" or pause as it is constantly going out to the internet to check various Outlook items. If I turn off my NIC and work off the Wifi everything works fine in Cached Mode....... but then I don't get the 1 GB internet speeds. I'm hoping someone has some ideas of what might be causing Outlook 365 problems when working on the NIC. As I said, this is a recent problem as everything had been working well prior to the last two weeks.
Thanks for your reply. I would have responded sooner but I am still trying to work through some problems. I have tried turning cached mode on and off as you suggested and the problem continues. And as I think I mentioned previously I had already tried creating a new user profile and that made no difference either. But I think this may just be a network driver error that has suddenly decided to surface after being stable for so long and has manifests in Outlook most prominently. As the problem continued I uninstalled the NIC driver and let Windows install whatever one it wanted. That seemed to help a bit but wasn't the cure since anytime cached mode was on Outlook wouldn't send any emails. And I really focused on the NIC since if I used the motherboard's wi-fi adapter (turning off the NIC first)everything in Outlook worked just fine. So it had to be some way that the NIC and Outlook were communicating with each other that is/was causing the problem.
As all the problems just started I assume at this point it probably was triggered by some combination of Windows update combined with and Outlook version that, combined with my NIC driver, was causing problems. So I went through some old directories on my computer and found one of the original driver packages from Intel (from 2018) and installed that, thinking I had little to lose and that by going way back in the driver history I might get the OS, Outlook, and the NIC to play nicely together. So far it seems to be working! Outlook is working in Cached mode, I am able to send emails, and the download/upload speeds are great. I just hope it stays like this........
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