Client Message Size Limits

powershellExchange 2013 enforces certain message size limits when it comes to client messages. These limits are in-place so clients can’t generate excessive load on your Exchange environment. These limits are determined for various access methods in multiple web.config files on Exchange Client Access Servers as well as Mailbox Servers.

Sometimes you may have good reasons to increase those limits. For example, when migrating to Office 365 using a product like MigrationWiz, you may want to increase the limit for Exchange Web Service (EWS) requests to allow for migration of larger items. Another example is when you want to allow for bigger attachments in Outlook WebApp (OWA). On TechNet, there’s an article on how to reconfigure these limits. However, the process consists of editing multiple web.config files, replacing multiple values in the same file, and following this process on each Exchange 2013 server in your environment. This is not only labor intensive and prone to error, but becomes tedious when you consider that each Cumulative Update will overwrite your web.config files.

But do not despair. To execute these changes for OWA and EWS, I have created a PowerShell script which will perform these tasks for you.

Requirements
Using the script requires Exchange 2013. You need to provide the server name (default is local server) or AllServers to apply to all Exchange 2013 servers in your environment. The script will modify the web.config remotely using the system share (e.g. C$), using the location of the Exchange installation, and uses IISRESET tool to restart IIS. It will create a backup of the web.config before modifying it.

Notes:

  1. The script checks for running in elevated mode when running against the local machine.
  2. Current version of the script requires Exchange Management Shell, to run Exchange cmdlets for checking installed roles a.o., as the web.config files which require editing depend on the installed roles.
  3. For OWA, add ~33% to the value you want to specify to compensate for encoding overhead.
  4. When connected to an Exchange server, the script processes the server hosting the EMS session last to prevent abortion caused by IIS reset.
  5. Script currently runs against Exchange 2013.

Usage
The script Configure-ClientSizeLimits.ps1 uses the following syntax:

.\Configure-ClientSizeLimits.ps1 [-Server |-AllServers] [-OWA ] [-EWS ] [-Reset] 

A quick walk-through on the parameters and switches:

  • Server specifies the server to configure. When omitted, it will configure the local server. This parameter is mutually exclusive with AllServers.
  • AllServers switch specifies to configure all Exchange 2013 servers. This switch is mutually exclusive with Server.
  • OWA configures the message size limit for OWA. Value is in 1KB units.
  • EWS configures the message size limit for EWS. Value is in 1KB units.
  • Reset switch specifies to perform an IISRESET against servers after reconfiguration of client-specific message size limits.

So, suppose you want to configure an OWA message size limit for you can use:

.\Configure-ClientSizeLimits.ps1 -Server EX01 -OWA 100 -EWS 10240 -Reset

Configure Client Size Limits If you want to configure EWS limits for all servers without resetting IIS, you could use:

.\Configure-ClientSizeLimits.ps1 -AllServers -EWS 10240

Download
You can download the script from the TechNet Gallery here.

Feedback
Feedback is welcomed through the comments. If you got scripting suggestions or questions, do not hesitate using the contact form.

Revision
See TechNet Gallery page.

To Do
Compatibility with Exchange 2010 and removal of dependency on Exchange Management Shell.

Exchange 2013 Cumulative Update 9

Ex2013 LogoThe Exchange Team released Cumulative Update 9 for Exchange Server 2013 (KB3049849). This update raises Exchange 2013 version number to 15.0.1104.5.

Cumulative Update reintroduces configuration of sent items for shared mailboxes, as was possible in Exchange 2010 but wasn’t available in Exchange 2013 yet. More information here.

Next to a security fix for MS15-064, this Cumulative Update contains the following fixes:

  • KB2983216 Category setting on an item in Outlook jumps the selection to the top of the list in an Exchange Server 2013 environment
  • KB2988660 Role assignment with custom write scope fails in an Exchange Server 2013 environment
  • KB3003978 Email messages are displayed with incorrect format in Outlook in an Exchange Server 2013 environment
  • KB3006849 GSSAPI-based Kerberos authentication protocol is not offered to IMAP clients in Exchange Server 2013
  • KB3009631 Advanced Find against the Sent Items folder in Outlook returns no result in Exchange Server 2013
  • KB3032153 Recurring events in Calendar over DST are not adjusted on all ActiveSync devices in all Exchange Server environments
  • KB3040681 MapiExceptionTimeout error during a hierarchy synchronization process of multiple public folders in Exchange Server 2013
  • KB3040683 System WLM overrides do not work when you do on-premises installations in Exchange Server 2013
  • KB3049081 OwaDeepTestProbe probe fails intermittently on a server that installs the Mailbox server role in Exchange Server 2013
  • KB3049771 Outlook Web App logon page takes longer time than expected to time out in an Exchange Server 2013 environment
  • KB3050825 EdgeTransport.exe starts to crash when PriorityQueuingEnabled is set to “True” in Exchange Server 2013
  • KB3050877 Emails that are sent as a secondary mailbox are not saved in the delegate’s Sent Items folder in Exchange Server 2013
  • KB3055940 “Object reference not set to an instance” error when you install cumulative update in Exchange Server 2013
  • KB3056045 “Cannot find Template User object” error when you find contacts that use a consumer domain in Exchange Server 2013
  • KB3056133 Exchange Server 2013 Activation time of transport rule is not displayed in UTC time
  • KB3056413 SMTP connection fails when you log on with a child domain account and use NTLM authentication in Exchange Server 2013
  • KB3056817 Update adds the Let me select the message option in Outlook Web App in an Exchange Server 2013 environment
  • KB3056822 Dynamics CRM 2013 stops synchronizing items from mailbox in an Exchange Server 2013 environment
  • KB3060825 The MSExchangeDelivery service crashes when you receive an email message from a specific sender in Exchange Server 2013
  • KB3064393 “Bad Command. 12” error and IMAP CAPABILITY commands are not offered in an Exchange Server 2013 co-existence environment
  • KB3068681 RPC encryption requirement is re-enabled for RPC Client Access Service after you upgrade server in Exchange Server 2013
  • KB3069060 Recurring meetings are accepted when their time conflicts on the same room mailbox in Exchange Server 2013
  • KB3069501 Duplicate folders are created after a mailbox move in Exchange Server 2013 Enterprise
  • KB3071427 Outlook Web App still downloads web beacon contents when you forward email messages in Exchange Server 2013

Notes:

  • If the new Set-Mailbox parameters for Sent Items configuration, i.e. MessageCopyForSentAsEnabled and MessageCopyForSendOnBehalfEnabled, are not available after installing this CU, run Setup /PrepareAD /IAcceptExchangeServerLicenseTerms explicitly.
  • When using Exchange hybrid deployments or Exchange Online Archiving (EOA), you are required to stay current.
  • Previously released CU7 introduced changes to prevent restoration of pre-CU7 databases. Pre-CU7 users are advised to perform a full backup post-upgrade to CU7 or later.
  • Previously released CU7 added support for hierarchies containing 250,000 modern public folders. Consult this article for co-existence scenarios.

This Cumulative Update does not include schema or Active Directory changes when compared to Cumulative Update 7. If you have deployed a version earlier than CU7, make sure you run PrepareSchema /PrepareAD.  If you want to speed up the Cumulative Update installation process, you can temporarily disable certificate revocation checking as described here.

Note that Cumulative Updates can be installed directly, i.e. no need to install RTM prior to installing Cumulative Updates. Note that once installed, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles. The order of upgrading servers is irrelevant, unlike with previous generations of Exchange.

Finally, and I can’t emphasize this enough: For any Hotfix, Rollup, Service Pack or Cumulative Update, I’d recommend to thoroughly test this in a test and acceptance environment first, prior to implementing it in production. When you lack such facilities, hold out a week or two and monitor the comments on the release article or TechNet forum for any issues.

You can download Exchange 2013 Cumulative Update 8 here; UM Language Packs can be found here.

Exchange 2013 Cumulative Update 8

Ex2013 LogoToday, Cumulative Update 8 for Exchange Server 2013 was released by the Exchange Team (KB3030080). This update raises Exchange 2013 version number to 15.0.1076.9.

This Cumulative Update introduces changes in the following areas:

  • Calendar and Contact Modern Public Folders favorites added in Outlook are now accessible in OWA.
  • Batch Migration of Public Folders to 2013 improves migration throughput and PF migration experience.
  • Increased support limits for Public Folders with Exchange on-premises deployments (500,000 for co-existence, or 1,000,000 for CU8-only deployments). Number of supported PF mailboxes stands at 100 though, with a per-PF mailbox limit of 100,000 Public Folders.
  • Supported EAS clients are now redirected to Office 365 upon successful Hybrid migration.

Next to DST corrections, this Cumulative Update introduces the following fixes:

  • 3045301 SMTP is not transported over TLS 1.1 or TLS 1.2 protocol in an Exchange Server 2013 environment
  • 3040681 MapiExceptionTimeout error during a hierarchy synchronization process of multiple public folders in Exchange Server 2013
  • 3037417 Outlook cannot download an OAB file in an Exchange Server 2013 environment that mixes Exchange Server 2010
  • 3037291 Can’t add members to Outlook contact group by using MAPI over HTTP
  • 3036952 Mailbox quota warning messages are not sent out after you migrate from Exchange Server 2010 to Exchange Server 2013
  • 3036374 Incorrect NDR size limit message is displayed for German localization in an Exchange Server 2013 environment
  • 3036365 “The specified address is not recognized or does not exist” error message in an Exchange Server 2013 environment
  • 3032153 Recurring events in Calendar over DST are not adjusted on all ActiveSync devices in all Exchange Server environments
  • 3031133 Default folders are duplicated after you migrate mailboxes to Exchange Server 2013
  • 3031069 Mails are spoofed in Office 365 or in an Exchange Server 2013 environment
  • 3030629 Outlook cannot open a shared folder on which a group you attend has the Reviewer permission in Exchange Server 2013
  • 3018518 Garbled text in the Japanese “From” field in a forwarded DBCS message
  • 3016440 Public folder mailbox quarantined
  • 3012266 Update to increase availability address spaces to 200 in Exchange Server 2013
  • 3011579 SaveChanges fails and generates a MAPI_E_NOT_FOUND error message on a large message body in Exchange 2013 CU6
  • 3006861 “The SMTP address has no mailbox associated with it” error when you access a user’s mailbox by using EWS application
  • 3003974 Improved support for MSG files in an Exchange Server 2013 environment where OPENTEXT products are used
  • 2988060 Cannot see the auditing results for an HttpModule-based extension for MAPI over HTTP protocol in Exchange Server 2013
  • 2986941 “An Active Directory error 0x51 occurred” error when you run the “Setup /PrepareAD” command from a DC in Exchange 2013
  • 2961741 Exchange Server 2013 delegated setup fails when the setup account is a member of Domain Admins

Notes:

  • When using Exchange hybrid deployments or Exchange Online Archiving (EOA), you are required to stay current.
  • Previously released CU7 introduced changes to prevent restoration of pre-CU7 databases. Pre-CU7 users are advised to perform a full backup post-upgrade to CU7 or later.
  • Previously released CU7 added support for hierarchies containing 250,000 modern public folders. Consult this article for co-existence scenarios.
  • Previously released CU5 introduced OAB architectural changes which are documented here. If you are affected, it is recommended to update CAS servers prior to Mailbox servers.

This Cumulative Update does not include schema or Active Directory changes when compared to Cumulative Update 7. If you have deployed a version earlier than CU7, make sure you run PrepareSchema /PrepareAD.  If you want to speed up the Cumulative Update installation process, you can temporarily disable certificate revocation checking as described here.

Note that Cumulative Updates can be installed directly, i.e. no need to install RTM or Service Packs prior to installing Cumulative Updates. Note that once installed, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles. The order of upgrading servers is irrelevant, unlike with previous generations of Exchange.

Finally, and I can’t emphasize this enough: For any Hotfix, Rollup, Service Pack or Cumulative Update, I’d recommend to thoroughly test this in a test and acceptance environment first, prior to implementing it in production. When you lack such facilities, hold out a week or two and monitor the comments on the release article or TechNet forum for any issues.

You can download Exchange 2013 Cumulative Update 8 here; UM Language Packs can be found here.

Role-based Access Control

security officer RBACIt has been over 5 years (wait, what?) since I wrote an article on Role-based Access Control, or RBAC, in Exchange 2010. At that time, RBAC was a big architectural change in Exchange 2010 over Exchange 2007.

Present day, RBAC is still a much neglected topic in many Exchange organizations. It must be said that most organization can happily live with the default RBAC configuration. They have no need to dive in this versatile model to set up granular permissions in their organization. In bigger organizations, this configuration can also easily become quite complex.

For TechTarget I started writing few articles on the topic of RBAC, starting with the base components. There you can find Part 1, Part 2, and Part 3.

Book: Pro Exchange 2013 SP1 PowerShell Administration

As some of you may have noticed, it has been a bit more quiet here than it used to be. Well, the reason for that, after several months of collaborative hard work, blood, sweat and tears, is finally here (and in stores just in time for the Holidays): A book titled Pro Exchange 2013 Service Pack 1 PowerShell Administration!

2013pa

Together with fellow Exchange MVP Jaap Wesselius, we will talk you through topics such as:

  • Deployment and co-existence scenarios.
  • The Client Access Server role and topics such as namespaces, certificates, load balancing, and publishing.
  • The Mailbox Server role and topics such as managing mailboxes, distribution lists and recipients, message transport
  • High availability topics like Database Availability Groups and Client Access and Transport availability.
  • Message Hygiene using the Edge Transport server role and anti-spam features.
  • Backup, Restore and Disaster Recovery, including the backup-less’ Native Data Protection scenario.
  • Unified Messaging features and integration with IP telephony solutions such as Microsoft Lync Server.
  • Compliance features like In-Place Archiving and MRM, In-Place Discovery, In-Place Hold, Data Loss Prevention including fingerprinting, and auditing.
  • Role-Based Access Control model and Split Permissions model for organizations that require this.
  • Office 365 and Exchange Online (EXO) scenarios, federating organizations, directory synchronization, ADFS and Multi-Factor Authentication, as well as basic tasks like onboarding and offboarding mailboxes.

Our 600+ page book will take a PowerShell-first approach when talking about Exchange Server 2013. You can order the book from Amazon here.

I have also added it to the book page here, which also contains other useful books when you want to learn about Exchange or related technologies like PowerShell, Active Directory or Lync Server.

Exchange 2013 Cumulative Update 7

Ex2013 LogoToday, Cumulative Update 7 for Exchange Server 2013 was released by the Exchange Team (KB2986485). This update raises Exchange 2013 version number to 15.0.1044.25.

Note: Customers that run backups of their Exchange databases are advised to upgrade to CU7 and perform a post-upgrade full backup. This is due to a race condition which could prevent proper restoration of pre-CU7 Exchange databases.

This Cumulative Update contains a security update to fix a potential elevation of privilege issue (bulletin MS14-075), as well as the following fixes:

  • 3004235 Exchange Server meetings in Russian time zones as well as names of time zones are incorrect after October 26, 2014
  • 3012655 New-MailboxImportRequest causes unreadable characters when you import an ANSI format .pst file of Russian language
  • 3012652 CalendarProcessing cmdlet does not generate delegate permissions to universal security groups in Exchange Server 2013
  • 3009631 Advanced Find against the Sent Items folder in Outlook returns no result in Exchange Server 2013
  • 3009612 Outlook Web App shows organization details on the contact card beyond the scope of user ABP in Exchange Server 2013
  • 3009291 Shared mailbox cannot be opened in Outlook in an Exchange Server 2013 environment that has multiple domains
  • 3008453 Cannot edit or delete forms from the organizational forms library in Exchange Server 2013
  • 3008438 User who is trying to Log on to Exchange Admin Console is logged in to OWA instead
  • 3006672 Move request fails if the IsExcludedFromProvisioning option is true in Exchange Server 2013
  • 3005391 Exchange Server 2013 Cumulative Update 5 breaks free|busy lookup from Exchange Online to Exchange Server 2007
  • 3003986 RejectMessageReasonText in transport rule appears in the user section of a DSN in Exchange Server 2013
  • 3001217 TLS 1.0 is hardcoded for SMTP traffic encryption in Exchange Server 2013
  • 3001037 Distribution group cannot send email messages to a mail enabled public folder in an Exchange Server 2013 environment
  • 2999031 A cross-forest mailbox move from Exchange Server 2007 to Exchange Server 2013 finishes with CompletedWithWarnings status
  • 2998144 New-MoveRequest cmdlet with RemoteLegacy parameter cannot perform a cross-forest mailbox move
  • 2988553 Add-ADPermission and Remove-ADPermission can be run outside the management scope in Exchange Server 2013
  • 2981538 Exchange Control Panel crashes when you proxy from Exchange 2013 to Exchange 2010
  • 3014051 Cannot migrate mailboxes in a multiple domains environment in Exchange Server 2013
  • 3012986 ContentIndexRetryQueueSize value for a passive node never drops to zero in Exchange Server 2013 Cumulative Update 6
  • 3004011 Sound alerts do not work in Outlook Web App when new email or calendar notification is received in Exchange Server 2013
  • 3003580 Event ID 4999 and 4401 when the Microsoft Exchange Replication service crashes in Exchange Server 2013
  • 3003518 “550 5.7.1” NDR when you send messages to external recipients in an Exchange Server 2013 hybrid environment
  • 3003068 Cannot see online archive mailbox after you upgrade to Exchange Server 2013 Cumulative Update 6
  • 3000944 Subfolders under the Deleted Items folder are not visible in Outlook in an Exchange Server 2013 environment
  • 2997847 You cannot route ActiveSync traffic to Exchange 2007 mailboxes after you upgrade to Exchange 2013 CU6
  • 2997355 Exchange Online mailboxes cannot be managed by using EAC after you deploy Exchange Server 2013 CU6
  • 2997209 Exchange Server 2013 databases unexpectedly fail over in a co-existence environment with Exchange Server 2007
  • 2995263 OAB cannot be rebuilt if the .flt file is larger than two GB in Exchange Server 2013
  • 2994216 PublicFolderMoveRequest deletes all read or unread state in target mailbox for each user in Exchange Server 2013
  • 2993871 Resource Booking Assistant crashes after you upgrade to Exchange Server 2013 Cumulative Update 5
  • 2983216 Category setting on an item in Outlook jumps the selection to the top of the list in an Exchange Server 2013 environment
  • 2931223 MAPI virtual directory is missing from Default Web Site node

Notes:

  • When using Exchange hybrid deployments or Exchange Online Archiving (EOA), you are required to stay current.
  • CU7 adds support for hierarchies containing 250,000 modern public folders. Consult this article for co-existence scenarios.
  • Be advised of OAB architectural changes introduced with CU5 which are documented here. If you are affected, it is recommended to update CAS servers prior to Mailbox servers.
  • If you have installed the Interim Update to fix Hybrid Configuration Wizard, you can install the Cumulative Update over it – there is no need to uninstall the IU prior to installing CU6.

This Cumulative Update includes schema and AD changes, so make sure you run PrepareSchema / PrepareAD. After updating, the schema version will be 15312. If you want to speed up the process, you can temporarily disable certificate revocation checking as described here.

Note that Cumulative Updates can be installed directly, i.e. no need to install RTM or Service Packs prior to installing Cumulative Updates. Note that once installed, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles. The order of upgrading servers is irrelevant, unlike with previous generations of Exchange.

Finally, and I can’t emphasize this enough: For any Hotfix, Rollup, Service Pack or Cumulative Update, I’d recommend to thoroughly test this in a test and acceptance environment first, prior to implementing it in production. When you lack such facilities, hold out a week or two and monitor the comments on the release article or TechNet forum for any issues.

You can download Exchange 2013 Cumulative Update 7 here; UM Language Packs can be found here.

Exchange 2013 Server Role Requirements Calculator 6.6

Ex2013 LogoNote: Shortly after publishing, a minor update was made in to fix circular referencing in the sheet.

Next to an updated Exchange 2010 Server Role Requirements calculator, the Exchange team published an update for the Exchange 2013 Server Role Requirements Calculator as well. The new version number is 6.5.

This new version includes a nice new feature, courtesey of Excel, which will plot mailbox usage using the provided input. You can find this chart on the Mailbox Space Modeling tab.

msm

Changes since version 6.5:

  • Fixed circular logic issue with initial mailbox size calculation

Changes since version 6.3:

  • New: The calculator now includes mailbox space modeling graphs that extrapolates (for each mailbox tier) the projected amount of time it will take to consume the mailbox quota.
  • Fixed “Number of Exchange Data Volumes per Server” to support more than 50 volumes.
  • Optimized memory sizing for FAST which reduces memory requirements for small mailbox server designs.
  • Added the ability to specify multiple AutoReseed volumes per DAG server to calculator and scripts.
  • Fixed 3 database/volume layout scenario involving 100 copies/server.
  • Fixed rounding error in calculating number of databases/volume in “2 Volumes / Backup Set”
  • Log isolation is now a calculated property to align with best practices guidance.
  • Changed “Disk” to “Vol” in left column of Distribution tab to align with scenarios that do not involve JBOD configurations.
  • Added additional processor core options.
  • Fixed JBOD storage design results table to accurately account for Restore Disk capacity being set to “–” and for differences between PDC and SDC Restore Disk capacity settings.
  • Fixed Backup Requirements worksheet to expose Weekly Full backups correctly.
  • Various comment changes/corrections.

You can download the calculator here. For more information, please consult the list of changes here or Read Me here.

Ex2013 CU6 & Ex2007 coexistence issue for EAS

Ex2013 LogoA short notice on an issue when you have deployed Exchange 2013 Cumulative Update 6 in coexistence in an Exchange 2007 environment. Exchange fellow Tony Redmond did a write-up on the issue here.

The issue prevents ActiveSync users whose mailbox reside on Exchange 2007 to authenticate properly when their requests are being proxied from Exchange 2013 CU6 to Exchange 2007. It has been identified in KB2997847. Alternatively, you direct Exchange 2007 EAS traffic directly to Exchange 2007 CAS servers when they are internet-facing and published.

Be advised that a previous known issue in this deployment scenario with delegates and dismounting stores has been identified in KB2997209.

Both articles provide links to request these hotfixes.

Another Exchange fellow, Jason Sherry, is keeping track of resolved and open Exchange 2013 CU6 issues here.

Exchange2013-KB2997355-FixIt-v2

Ex2013 LogoAs mentioned earlier, when you have deployed Exchange Server 2013 Cumulative Update 6 in a Hybrid deployment, several Office 365-related mailbox functions will not show up in the Exchange Admin Center (EAC). The issue was identified by Microsoft in KB2997355 and a fix was published.

However, the script to fix the issue looks for the XAML file in the default Program Files folder, using the default Exchange installation folder. Better is to check the actual Exchange installation folder, which can easily be accomplished in Exchange Management Shell using the $exinstall environment variable, or by reading the folder from the registry.

To help those installing Exchange in a non-default installation folder, and I know there are quite a few of you out there, who are hesitant to correcting the installation path in the provided FixIt script, I have create an alternative version of the Exchange2013-KB2997355-FixIt script. This version will read the installation path from the registry. Not disturbing but changed as well is correcting the XAML file in one go, unlike the official script which performs 3 consecutive read/modify/write actions on the same file.

You can download the Exchange2013-KB2997355-FixIt-v2.ps1 script here.

 

Exchange 2013 Cumulative Update 6

Note: There are some known issues with CU6 RTM concerning Hybrid environments and when used in co-existence with Exhange 2007. Please check this post for updates.

Today, Cumulative Update 6 for Exchange Server 2013 was released by the Exchange Team (KB2936880). This update raises Exchange 2013 version number to 15.0.995.29.

This Cumulative Update increases the Public Folder for Exchange On-Premises to 100,000. It also fixes the ‘Hybrid Configuration Wizard ‘Subtask Checkprereqs Execution Failed’ issue I blogged about here (2988229).

This Cumulative Update contains the following fixes:

  • 2983512 RPC Client Access service crashes on an on-premises Mailbox server in an Exchange Server 2013 hybrid environment
  • 2983426 AutodiscoverSelfTestProbe fails when external URL is not set for EWS virtual directory in Exchange Server 2013
  • 2983423 AutodiscoverSelfTestProbe fails when external URL is not set for ECP virtual directory in Exchange Server 2013
  • 2983422 The ServerWideOffline component is set to Inactive after Exchange Server 2013 prerequisite check fails
  • 2983207 “532 5.3.2” NDR when you send an email message to a hidden mailbox in an Exchange Server 2013 environment
  • 2983066 Removed Default or Anonymous permission for Outlook folders cannot be restored in an Exchange Server 2013 environment
  • 2982769 “Topology service cannot find the OWA service” when you perform an eDiscovery search in Exchange Server 2013
  • 2982763 Mail-enabled public folder accepts email messages from unauthorized users in an Exchange Server 2013 environment
  • 2982762 OAB generation arbitration mailbox can be removed or disabled in an Exchange Server 2013 environment
  • 2982760 The Enter key submits duplicate sign-in forms to Outlook Web App in an Exchange Server 2013 environment
  • 2982759 You cannot access the archive mailbox of a delegated user after enabling MAPI over HTTP
  • 2982017 Incorrect voice mail message duration in an Exchange Server 2013 environment
  • 2981835 You cannot add attachments, delete or move many email messages in bulk in Outlook Web App
  • 2981466 MAPI/CDO client cannot connect to Exchange Server 2013
  • 2977279 You cannot disable journaling for protected voice mail in an Exchange Server 2013 environment
  • 2975599 Exchange Server 2010 public folder replication fails in an Exchange Server 2013 environment
  • 2975003 Calendar item body disappears in Outlook online mode in an Exchange Server 2013 environment
  • 2974339 OAB generation fails if FIPS is used in an Exchange Server 2013 environment
  • 2971270 Blank page after you sign in to Exchange Server 2013 EAC (formerly ECP)
  • 2970040 Folder Assistant rule does not work correctly in an Exchange Server 2013 environment
  • 2965689 EAS device cannot sync free/busy status if an item is created by EWS in an Exchange Server 2013 environment
  • 2963590 Message routing latency if IPv6 is enabled in Exchange Server 2013
  • 2961715 “Something went wrong” error in Outlook Web App may show an incorrect date
  • 2958434 Users cannot access mailboxes in OWA or EAS when mailbox database is removed

Notes:

  • There are some additional changes in the way Public Folders operate. Consult this article from the Exchange team for details on these changes.
  • When using Exchange hybrid deployments or Exchange Online Archiving (EOA), you are required to keep up to date.
  • Be advised of OAB architectural changes introduced with CU5 which are documented here. If you are affected, it is recommended to update CAS servers prior to Mailbox servers.
  • If you have installed the Interim Update to fix Hybrid Configuration Wizard, you can install the Cumulative Update over it – there is no need to uninstall the IU prior to installing CU6.

This Cumulative Update includes schema and AD changes, so make sure you run PrepareSchema / PrepareAD. After updating, the schema version will be 15303.

Note that Cumulative Updates can be installed directly, i.e. no need to install RTM or Service Packs prior to installing Cumulative Updates. Note that once installed, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles. The order of upgrading servers is irrelevant, unlike with previous generations of Exchange.

Finally, and I can’t emphasize this enough: For any Hotfix, Rollup, Service Pack or Cumulative Update, I’d recommend to thoroughly test this in a test and acceptance environment first, prior to implementing it in production. When you lack such facilities, hold out a week or two and monitor the comments on the release article or TechNet forum for any issues.

You can download Exchange 2013 Cumulative Update 6 here; UM Language Packs can be found here. More details about these changes, preparing Active Directory or installing this Cumulative Update can be found in the original announcement.