Customize Exchange 2016 Outlook on the Web Sign in Page


Outlook on the web (formerly known as Outlook Web App or Outlook Web Access) is a browser-based exchange client that let you access your mailbox from almost any web browser supported by Microsoft Exchange. Once you’ve installed Exchange 2016 in your organization, one of the optional step that you might want to perform is to customize Exchange 2016 Outlook on the Web Sign in Page to provide a corporate look and feel to the end users. In this blog post, we’re going to customize the Outlook on the Web Sign in page for our users.

What we can Customize?

One of the question that you can think is “What we can customize” in outlook on the web client? Microsoft gives you the option to customize the following sign in page for your organization.

  • Sign in Page Customization
  • Error Page Customization

You can customize the color and images of these pages. These pages are based on CSS files in your exchange installed directories. Once you modify the CSS file for these pages it will be reflected to the users in the organization.

Make sure you back up before customizing the outlook on the web pages.

How to Customize Exchange 2016 Outlook on the Web?

To customize exchange 2016 outlook on the web sign in page, follow the following steps.

  • Login to Exchange 2016 Server as an administrator
  • Navigate to “C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\owa\auth\15.1.396\themes\resources”. In my case exchange is installed on C Drive. You can also navigate this path from IIS as shown below.

Customize Exchange 2016 Outlook on the Web Sign in Page

If you have multiple Exchange Servers then you must copy the modified files to each server.

  • Modify or replace the owa_Text_Blue.png, Olk_logo_White.png and favicon_ico images as per your company requirements.

Customize Exchange 2016 Outlook on the Web Sign in Page

  • Make sure that you match the size of the image. Replace the updated images with the existing one and reload the OWA page.
  • Below is the updated OWA page. I’ve modified the 2 images.

Customize Exchange 2016 Outlook on the Web Sign in Page


Exchange 2010 to Exchange 2016 Migration – Part 1

Exchange 2010 to Exchange 2016 Migration


With the release of Exchange 2016, Microsoft brings latest cloud based enhancements of Office 365 to on prem version of Exchange. In this series, We will go through the steps required for Exchange 2010 to Exchange 2016 migration and move mailboxes from Exchange 2010 to 2016 to let the users to use new features of Exchange 2016.

In this series, I’m going to use my test environment where I’ve 1 Exchange 2010 Standard Server deployed with Active Directory running on Windows Server 2008 R2 with domain and forest functional level of 2008R2.

Currently Exchange Services are configured as below.

Exchange 2010 to Exchange 2016 Migration - Part 1

Below table depicts the Server Name, IPs, Active Directory Site and Server Roles installed.

Exchange 2010 to Exchange 2016 Migration - Part 1



Plan Exchange 2010 Upgrade

Before you start Exchange 2016 deployment in existing exchange 2010 organization it’s important to understand the key architectural differences between Exchange 2010 and 2016.

Exchange 2016 includes two server roles Mailbox and Edge Transport server roles. The Edge Transport server role needs to be installed on its own computer. It can’t be installed on the same computer as the Mailbox server role. The Edge Transport Server role in optional but Mailbox server role is mandatory.

You need to plan for following before exchange 2016 installation.

  • Active Directory Schema
  • Namespace for Exchange 2016
  • SSL Certificate
  • Hardware Sizing for Exchange 2016
  • High Availability of Exchange 2016
  • Mail flow
  • End user Impact
  • End user Communication
  • Exchange 2010 Health Check

Active Directory Schema

Exchange 2016 installation requires you to update Active Directory Schema to extend objects and attributes to support Exchange 2016. You need to carefully plan about Active Directory Schema update. You cannot roll back Schema Update, the only way to roll back is to manually remove the entries from schema and it’s not a recommended method.

You need to have Active Directory Schema Admin, Enterprise Admin, Domain Admin and Exchange Organization Admin rights to install Exchange 2016

In our scenario we’ve single Exchange 2010 and our schema is extended with 2010. We’ll be extending the schema to 2016 during the installation of Exchange 2016.

If you have Exchange 2010 deployed and upgrading to 2016 then make sure that you plan your schema upgrade. If you do not have Exchange 2013 installed in exchange 2010 organization or AD Schema isn’t extended for Exchange 2013 then once Schema is extended for Exchange 2016 you’ll not be able to add Exchange 2013 server in your organization.

Namespace for Exchange 2016

Plan the namespace configuration for Exchange 2016. Services that you’re going to transition from Exchange 2010 to 2016 like Autodiscover, Outlook on the Web a.k.a OWA, Exchange Web Services, legacy, office online etc. Exchange 2010 coexistence with Exchange 2016 allows you to share the namespace configuration to reduce the complexity of Exchange upgrade. It’s recommended to use the same namespace configuration for Exchange 2016 to make it easy transition across the board. We are going to use the following namespace configuration in our upgrade.

Exchange 2010 to Exchange 2016 Migration - Part 1


Note: You do not need legacy namespace for Exchange 2016 coexistence with 2010. I have legacy URL because sometimes during the upgrade, customers would like to use a new namespace for 2016.

I have not included the namespaces for Office Online Server as we are not going to deploy Office Online Server. Apart from Exchange Services namespace planning, we also need to plan the naming convention for Exchange 2016 installation like Exchange 2016 hostname, Database naming convention etc.

SSL Certificate

As we have planned the namespace configuration, next step is work on Exchange 2016 SSL certificate. New SSL certificate will include all the namespaces mentioned above. SSL certificates are used to protect the communication between your Exchange organization and external organizations. It’s recommended to use public SSL certificate for exchange services. For our exchange upgrade purpose, we’re going to use a SSL certificate from Digicert that will include the following entries.


It’s recommended to use Subject Alternative Names certificate. Wild card certificate is also supported with Exchange 2016.

Hardware Sizing for Exchange 2016

Exchange Server sizing is an important factor in our deployment. Under-sizing or over-sizing of exchange environment can cause significant issues with your messaging infrastructure. It’s recommended to use Exchange Server Role Requirements Calculator. After working with exchange server role calculator, below are the recommendations of calculator for Exchange 2016 hardware.

  • 2 vCPU
  • 16GB RAM
  • 100 GB of Operating System Drive
  • 24GB Page file
  • RAID 1 for Exchange 2016 Databases
  • 2 Exchange 2016 Databases are recommended


Sizing is being done for 100 users running on Exchange 2010. We’re going to have a High Availability in Primary site only.

High Availability of Exchange 2016

To avoid single point of failure in primary site, Exchange 2016 will be configured in high availability mode by using Database Availability Groups.

Mail Flow

After the installation of Exchange 2016 server, the first step is to cutover the mail flow from Exchange 2010 to Exchange 2016. It’s important to plan your mail flow changes. In case something goes wrong the impact will be on all the users within the organization. Once we have exchange 2016 installed, we are going to use the following mail flow.

new mail flow

As you can see in the diagram, We’re going to move the mail flow from Exchange 2010 to Exchange 2016 servers once we’ve exchange 2016 installed, configured and tested.

End User Impact

It’s important to plan for end user impact beforehand. Exchange 2016 doesn’t support Outlook client 2007 or 2003. Make sure that you’ve analyzed and reviewed the end user impact before you migrate your users from Exchange 2010 to 2016. Update your endpoints to minimum supported version of outlook and IE. It’s recommended to install the latest updates of outlook client to provide best possible experience to end users when connecting with Exchange Server. Currently Exchange 2016 support following outlook clients.

  • Outlook 2016
  • Outlook 2013
  • Outlook 2010 with April 2015 Updates
  • Outlook for Mac for Office 365
  • Outlook for Mac 2011

Outlook clients earlier than Outlook 2010 are not supported. Email clients on Mac operating systems that require DAV, such as Entourage 2008 for Mac RTM and Entourage 2004, are not supported with Exchange 2016.

End User Communication

End user notifications planning help dictate a smooth and successful migration.  It is recommended that the changes end users will encounter and how to overcome them be communicated in detail and with enough advance notice that the end users have time to ask questions and understand what is expected of them.

Although mailbox migration from Exchange 2010 to 2016 will not have any impact to end user apart from a pop up message in outlook client but it’s recommended to notify the end user and provide adequate information to the user so that they can perform basic troubleshooting in case they ran into any issue after their mailbox is being migrated from Exchange 2010 to 2016.

Exchange 2010 Health Check

It’s always a good experience to perform health check of your existing Exchange 2010 server before you upgrade or deploy Exchange 2016 in your exchange organization. Exchange 2010 health check will help you determine the health of your existing system and you can fix any issues that can cause significant impact to your transition to Exchange 2016. Healthy exchange 2010 will help a lot in a smooth transition to Exchange 2016. Exchange 2010 health check will be performed before the installation of Exchange 2016.


In part one of this series we worked on planning of Exchange 2016 upgrade and reviewed some of the important key factors to consider before upgrading to Exchange 2016. In the next part of this series, we will start the exchange 2016 installation and configuration by first completing the action items of planning phase.

If you would like to read the other parts of this blog article series please go to:

Remove Exchange Server using ADSI Edit

What is ADSIEdit?

Active Directory Service Interfaces Editor is a Lightweight Directory Access Protocol editor that you can use to manage objects and attributes in Active Directory. It provides a detailed view of every object and attribute in your Active Directory forest. You can query, view and modify attributes using ADSIEdit.

Important: ADSI Edit must be handled with care. Modifying the attributes using ADSIEdit can cause significant issues with your infrastructure if something is done in a wrong way.

When to use ADSI Edit for Exchange?

I usually don’t recommend to use ADSI Edit for exchange related tasks but sometime I’ve seen scanerios where the only solution that is available for us is to use ADSIEdit to clean and fix Exchange issues. Few of these scanerio’s are as below.

  • Removing Exchange Server Attributes for old decommissioning of Exchange
  • Exchange Server is offline and needs to be removed from Active Directory
  • Exchange installation did not finish properly and attributes need to be removed
  • Removed Public Folder Database attributes
  • Remove other Exchange attributes related to Database or services

How to remove Exchange Server using ADSI Edit?

Follow the following steps to remove Exchange Server using ADSI Edit.

  • Login to domain controller with administrative account.
  • Navigate to Start –> Run –> ADSIEdit.msc and hit enter
  • Click on Action –> Connect to –> Select Configuration under “Select a well known naming Context:”


  • Navigate to CN=Configuration, DC=MSCloudTalks, DC=COM

Replace DC=MSCloudTalks, DC=COM with your domain name

  • Expand the CN=Services –> CN=Microsoft Exchange



If your exchange server is permanently offline and you do not want to bring it online again, then simply remove CN=Microsoft Exchange and CN=Microsoft Exchange Autodiscover

  • If you want to remove a specific Exchange server which wasn’t installed or uninstalled properly then navigate to CN=Microsoft Exchange >CN=CloudTalks>CN=Administrative Groups>CN=Exchange Administrative Group(FYD12345789)>CN=Servers



  • Select the Exchange Server from right hand side and delete the server.
  • Once the server is deleted from ADSI Edit, Update the Schema and run AD Replication.
  • Reinstall the operating system on deleted Exchange server and use the hardware the other services.


Sometimes We came across scenarios where the only solution is to use ADSI Edit to completely remove Exchange server from Active Directory domain but using the ADSI tool can be harmful in a way that if you delete a wrong server by mistake then the impact will be on all users using the service. Also, I do not recommend to use ADSI Edit in first go. You always have ADSI workaround as last resort to remove Exchange server and attributes from Active Directory Domain. Also, make sure you have a full back up of you AD and Exchange infrastructure before removing anything from ADSI Edit.

Understanding Office 365 Cutover Migration

What is Cutover Migration?

Office 365 provides multiple migration option to the customers based on source messaging systems. We can either use Office 365 based native migration tools or we can leverage 3rd party toolset like BitTitan, Quest and many more tools to migrate mailbox data from source messaging system to office 365.

Cutover Migration is defined as “The process of migrating on premises Exchange mailboxes to office 365 in a single migration batch. Migration batch migrate on premises mailboxes, distribution lists and Mail Contacts to Office 365”

Office 365 provides customer with a native cutover migration tool that can migrate user’s email, contacts, calendar and tasks from Exchange 2003, 2007 and 2010 to Office 365 without requiring additional licenses for data migration.

The WindowsEmailAddress attribute is used as the primary key for the cutover migration and changing the WindowsEmailAddress attribute during a cutover migration isn’t recommended.

Outlook Anywhere must be functional to use Native Office 365 Cutover Migration tool.

How Cutover Migration Works?

Thanks to Microsoft for below Diagram that shows how a cutover migration works.

Understanding Office 365 Cutover Migration


What you need to plan about Cutover Migration?

Before you start migrating your users using native cutover migration tool, below is the information that you must be aware of as an administrator.

  • Exchange online connects with on prem exchange server using outlook anywhere. Outlook Anywhere must be working properly if you want to leverage Native Cutover tool.
  • Based on Address book, exchange online will spun up user mailboxes, Distribution List and Mail Contacts in Exchange online and start initial synchronization process. Hide the user mailbox, Distribution list and Mail Contact in address book if you do not want to synchronize to Office 365.
  • Native Cutover Migration tool will not migrate Dynamic Distribution Groups and Public Folders to Office 365.
  • Cutover Migration tool will migrate Shared Mailboxes as user mailbox in Office 365. After the cutover you need to manually convert those mailboxes to Shared Mailbox in Office 365.
  • Distribution groups will be migrated with Default permissions in Office 365. By default office 365 Distribution Groups aren’t allowed to receive external emails. If you have any Distribution group that receive external email then modify the settings after the migration.
  • Cutover Migration support up to 2000 mailboxes to be migrated. If you’ve more then 2000 mailboxes in Exchange then you need to choose a different migration option. It’s recommended to use Cutover Migration for up to 150 mailboxes.
  • All users have to reconfigure Outlook and Active Sync clients after the public DNS cutover to Office 365.
  • Directory Synchronization isn’t supported with Native Cutover tool. If you want to leverage Directory Sync tool then you can deploy the tool after the cutover migration.
  • Native Cutover tool will perform delta synchronization after every 24 Hrs once the initial sync is completed for up to 90 days. Migration batch will be automatically stopped after 90 days.
  • Administrator needs to complete the migration within 90 days. Once the batch is stopped after 90 days. It will be automatically deleted within 30 days.
  • Your SMTP domain must be added in Exchange online as Accepted Domain. Once the domain ownership is verified in Office 365 it will be automatically added to Accepted domains.
  • You must communicate your end users with the transition to Office 365.

For more information please read following Microsoft articles.

Rename Exchange 2016 Default Database

Just like previous version of Exchange, Exchange 2016 installation also creates a default database with the name “Mailbox Database 123456789” in default installation directory. In my case, the default database is being created at If you installed Exchange to the default path then the mailbox will be stored in “C:\Program Files\Microsoft\Exchange Server\V15\Mailbox\”.

It’s not recommended to install Exchange server on operating system drive.

One of the Exchange 2016 Post-Installation step is to rename the default database as per the naming convention used by your organization. There are two methods available to rename your database in Exchange 2016.

  • Rename Exchange 2016 Database from GUI
  • Rename Exchange 2016 Database from Exchange Management Shell

Rename Exchange 2016 Database from GUI

To rename your database using GUI method, follow the following steps.

  • Login to Exchange Admin Center.
  • Navigate to Exchange Admin Center –> Servers –> Databases
  • Select the database and click on Edit

Rename Exchange 2016 Default Database

  • Enter the new name of the Database in “Name” field and Click on Save

Rename Exchange 2016 Default Database

  • You’re done with the renaming of  your database using Exchange Admin Center.

Rename Exchange 2016 Database

Rename Exchange 2016 Database from Exchange Management Shell

Another method of renaming your Exchange 2016 database is to use Exchange Management Shell. To rename your database using EMS, follow the following steps.

  • Run Exchange Management Shell as Administrator
  • Run the following cmdlet in Exchange Management Shell
    • Set-MailboxDatabase -Identity “Database01” -Name DB01

Rename Exchange 2016 Default Database

In my case, I’ve renamed my Database01 database to DB01 using EMS

  • To verify that the database is renamed, run the following cmdlet to retrieve database information
    • Get-MailboxDatabase | ft Name, Server

Rename Exchange 2016 Default Database


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