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This update also includes new daylight saving time (DST) updates for Exchange Server 2016. For more information about DST, see Daylight Saving Time Help and Support Center.

Known issues in this cumulative update

In multidomain Active Directory forests in which Exchange is installed or has been prepared previously by using the /PrepareDomain option in SETUP, this action must be completed after the /PrepareAD command for this cumulative update has been completed and the changes are replicated to all domains. Setup will try to execute the /PrepareAD command during the first server installation. Installation will finish only if the user who initiated SETUP has the appropriate permissions.

Issues that this cumulative update fixes

This cumulative update fixes the issues that are described in the following Microsoft Knowledge Base articles:

  • 4487596 Emails are blocked in moderator mailbox Outbox folder when you send large volumes of emails in Exchange Server 2016

  • 4456241 You receive a meeting request that has a "not supported calendar message.ics" attachment in Exchange Server 2016

  • 4456239 New-MailboxRepairRequest doesn't honor RBAC RecipientWriteScope restrictions in Exchange Server 2016

  • 4487591 The recipient scope setting doesn't work for sibling domains when including OUs in the scope in Exchange Server 2016

  • 4468363 MRM does not work for mailboxes that have an online archive mailbox in Exchange Server

  • 4487603 "The action cannot be completed" error when you select many recipients in the Address Book of Outlook in Exchange Server 2016

  • 4488076 Outlook on the Web can't be loaded when users use an invalid Windows language in operating system in Exchange Server 2016

  • 4488079 Exchange Server 2016 allows adding Exchange Server 2019 mailbox server into a same DAG and vice versa

  • 4488077 Can't configure voice mail options when user is in different domain in Exchange Server 2016

  • 4488263 X-MS-Exchange-Organization-BCC header isn't encoded correctly in Exchange Server 2016

  • 4488080 New-MigrationBatch doesn't honor RBAC management scope in Exchange Server 2016

  • 4488262 Delivery Reports exception when tracking a meeting request that's sent with a room resource in Exchange Server 2016

  • 4488268 Disable the irrelevant Query logs that're created in Exchange Server 2016

  • 4488267 Test-OAuthConnectivity always fails when Exchange Server uses proxy to connect to Internet in Exchange Server 2016

  • 4488266 Client application doesn't honor EwsAllowList in Exchange Server 2016

  • 4488265 "There are problems with the signature" error occurs for digital signature message if attachment filtering is enabled in Exchange Server 2016

  • 4488264 Mailbox that has a bad move request can't be cleaned up from destination mailbox database in Exchange Server 2016

  • 4488261 Event ID 1002 when the store worker process crashes in Exchange Server 2016

  • 4488260 New-MailboxExportRequest and New-MailboxImportRequest don't honor RBAC management scope in Exchange Server 2016

  • 4488259 MailTip shows wrong number of users for a distribution group if the users are in different domains in Exchange Server 2016

  • 4488258 OAuth authentication is removed when saving MAPI virtual directory settings in EAC in Exchange Server 2016

  • 4490060 Exchange Web Services Push Notifications can be used to gain unauthorized access

  • 4490059 Reducing permissions required to run Exchange Server using Shared Permissions Model

Get Cumulative Update 12 for Exchange Server 2016

Download Center

Download Download Cumulative Update 12 for Exchange Server 2016 (KB4471392) now.

Download Download Exchange Server 2016 CU12 UM Language Packs now.


  • The Cumulative Update 12 package can be used to run a new installation of Exchange Server 2016 or to upgrade an existing Exchange Server 2016 installation to Cumulative Update 12.

  • You don't have to install any previously released Exchange Server 2016 cumulative updates or service packs before you install Cumulative Update 12.

File Information

File hash information

File name

SHA1 hash

SHA256 hash





Exchange server file information

Download the list of files that are included in this security update 4471392.

How to get help and support for this security update

Help for installing updates: Protect yourself online

Help for protecting your Windows-based computer from viruses and malware: Microsoft Security

Local support according to your country: International Support

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