Precautionary Measures:

1. Take the backup of your AD Architecture & Exchange 2003 Information store and test / verify the backup as explained in above figure.
2. Update Active Directory Functional Levels (Both Forest & Domain) to Windows 2003 (min).
3. Change MS Exchange 2003 Mode (from Mix) to Native.
4. If there's only MS Windows 2003 Domain architecture then atleast update its schema to MS Windows 2008 (@ minimum if you don't want to add ADC of MS Windows 2008).
5. Before launching setup of MS Exchange 2010, set MS Exchange 2003 permissions using Media of MS Exchange 2010 (i.e. Setup.com /PrepareLegacyExchangePermissions)
6. Start deployment in Internet Facing AD Site.

What is Internet Facing AD-Site?

Some time it makes some confusions when you think of AD + internet means you have to expose your AD to the internet. No Way! Actually it means "you must have an Active Directory site that has internet connectivity, typically through a router and preferably through a firewall too" simple! isn't it?

Environment Scenario

Single Forest Single Tree architecture of AD using MS Windows 2003 R2 Enterprise 32bit with Forest and Domain functional level “MS Windows 2003”. MS Exchange 2003 SP2 is installed and now going to start the transitioning phase with Co-existence.

Step#1 - Updating AD-Schema Using MS Windows 2008 Server Media

Admin Rights are required for updating the Active Directory Schema. Before you start, follow some of the important guidelines.

1. On the TLD (Top Level Domain holding Schema Master Role), using elevated command prompt (right click on the command prompt application and select run as administrator), enter following command.
2. Upgrade Forest using MS Windows 2008 Media with the following command

a.       Adprep32 /forestprep

b.      Adprep32 /DomainPrep

c.       Adprep32 /Domainprep /ugprep

Note: if the OS is x64bit then Adprep.exe command would used instead of AdPrep32.exe as mentioned above.

Deploying MS Windows 2008 Server R2 / MS Windows 2012 as an Additional Domain Controller - ADC

1. Prepare Additional Domain Controller (MS Windows 2008 / 2012) right after this upgrade.
2. Configure DNS Settings on ADC and verify NTFRS replication.
3. Transfer FSMO Roles from MS Windows 2003 to MS Windows 2008

a.       For Transferring Schema Master apply the following command on the server having Schema master FSMO

                                                               i.      regsvr32 schmmgmt.dll

                                                             ii.      Open MMC console and Add Schema Management snap-in

                                                            iii.      Connect to the transferring Domain Controller and Transfer the roles

Note:  Step#3 is an optional thing, if you do not want to transfer FSMOs then its fine you can run your environment without transferring FSMOs to Windows 2008 server but Windows 2008 ADC existence is important for deployment of MS Exchange 2010 Server.

Deploying MS Exchange 2010 Server in a Co-existence of MS Exchange 2003 Server

Using elevated Command prompt, change the directory to MSEx2010 m>Note:  Step#3 is an optional thing, if you do not want to transfer FSMOs then its fine you can run your environment without transferring FSMOs to Windows 2008 server but Windows 2008 ADC existence is important for deployment of MS Exchange 2010 Server.

Deploying MS Exchange 2010 Server in a Co-existence of MS Exchange 2003 Server

a.       Setup.com /PrepareLegacyExchangePermissions

1.

Coexistence of Exchange 2010 and earlier versions of Exchange Server

 Hardware Requirements for MS Exchange 2010 Standard Server

Operating System Support for MS Exchange 2010 Standard server

When Deploying CAS take care of below mentioned points

a.   DNS settings for URLs and their IPs as explained in below figure.

b.   Certificates Installation, import / export in between MS Exchange 2010 CAS and MS Exchange 2003 Front / back end servers.

c.    For single sign-on you need to keep both of the servers owa security settings same.

d.    Initiate a redirection of owa request to MS Exchange 2003 if users are available on MS Exchange 2003 backend server.

1. Open MS Exchange 2010 PowerShell
2. Get-OwaVirtualDirectory
3. Set-OwaVirtualDirectory –Identity “owa (Default Web Site)” –Exchange2003URL https://legacy.ex2003server.com –internalURLhttps://ex2010.domain.com –externalUrl https://mail.domain.com

To verify that security settings are identical and there is no problem in configurations simplytype below command in the MS Exchange 2010 PowerShell "Get-OwaVirtualDirectory |fl"

For single sing-on turn on form based authentication on MS Exchange 2003 Server 
using its HTTP properties. Now, check and confirm the redirection. After successful,
deployment of CAS now install HUB on the same or on a separate but with in the same 
domain. For both of the server to communicate or exchange email with each other below 
workout is important only if you got any problem in email send or receive. 

Workout for initiating emails in between two email servers.

1. Start Exchange Management Console.
2. Expand Server Configuration and then click Hub Transport.
3. Click the Receive Connectors tab.
4. Locate the remote Exchange server receive connector that the e-mail message is trying to be sent to. 

1. Start Exchange Management Console.
2. Expand Server Configuration and then click Hub Transport.
3. Click the Receive Connectors tab.
4. Locate the remote Exchange server receive connector that the e-mail message is trying to be sent to. 
send protocol logs from the server that the e-mail message is stuck in.



5. Right-click the receive connector and then click Properties. 

Note: This is typically the Default server_name receive connector for the remote Exchange server, unless modifications were made. If you are not sure which connector is used, receive protocol logs shows the receive connector that is used.



6. On the Authentication tab, make sure that the Exchange Server authentication check box is selected. 


For Microsoft Exchange Server 2003 remotes servers:
1. Start Exchange System Management.
2. Expand the Servers container.
3. Under the problematic remote Exchange server, locate to the Protocols container.
4. Expand the Protocols container, right-click SMTP.
5. Right-click Default SMTP Virtual Server and then click Properties.
6. Click the Access tab and then click Authentication.
7. Make sure that the Integrated Windows Authentication check box is selected.


De-Commissioning of MS Exchange 2003.

1. Move All Mailboxes from MS Exchange 2003 to MS Exchange 2010 
2. Move All Replications of Public Folders to MS Exchange 2010 
3. Move All OAB to MS Exchange 2010 using its EMC 
4. Move RUS (Recipient Update Service) to MS Exchange 2010 using MS Exchange 2003 Management Console 
5. Delete / Remove MS Exchange 2003 Public Folders 
6. Uninstall MS Exchange 2003 Server 
7. Check functionality of MS Exchange 2010 Server. 
8. Uninstall MS Windows 2003 Domain after proper DNS settings transfer etc. 
9. Recheck MS Exchange 2010 Server Functionality.

 

Co-existence of MS Exchange 2010 with MS Exchange 2013 CU-1

 

Once MS Exchange 2003 has been demoted successfully, we shall move on to inject MS Exchange 2013 server by updating AD Schema and Installing MS Exchange 2013 CU1. The same procedure for email routing would be adopted. Later on mailboxes must be moved from legacy exchange version to MS Exchange 2013 using Management Console of MS Exchange 2013 as shown in the figure below:



Coexistence of Exchange 2013 and earlier versions of Exchange Server

 

Exchange version	Exchange organization coexistence
Exchange Server 2003 and earlier versions	Not supported
Exchange 2007	Supported with the following versions of Exchange: Update Rollup 10 for Exchange 2007 Service Pack 3 (SP3) on all Exchange 2007 servers in the organization, including Edge Transport servers. Exchange 2013 Cumulative Update 1 (CU1) on all Exchange 2013 servers in the organization.
Exchange 2010	Supported with the following versions of Exchange: Exchange 2010 SP3 on all Exchange 2010 servers in the organization, including Edge Transport servers. Exchange 2013 CU1 on all Exchange 2013 servers in the organization.
Mixed Exchange 2010 and Exchange 2007 organization	Supported with the following versions of Exchange: Exchange 2010 SP3 on all Exchange 2010 servers in the organization, including Edge Transport servers. Exchange 2013 CU1 on all Exchange 2013 servers in the organization.
Supported with the following versions of Exchange: Update Rollup 10 for Exchange 2007 SP3 on all Exchange 2007 servers in the organization, including Edge Transport servers. Exchange 2010 SP3 on all Exchange 2010 servers in the organization, including Edge Transport servers. Exchange 2013 CU1 on all Exchange 2013 servers in the organization.

Hardware requirements for Exchange 2013

 

Component	Requirement
Processor	x64 architecture-based computer with Intel processor that supports Intel 64 architecture (formerly known as Intel EM64T) AMD processor that supports the AMD64 platform Intel Itanium IA64 processors not supported
Memory	Varies depending on Exchange roles that are installed: Mailbox   8GB minimum Client Access   4GB minimum Mailbox and Client Access combined   8GB minimum
Disk space	At least 30 GB on the drive on which you install Exchange An additional 500 MB of available disk space for each Unified Messaging (UM) language pack that you plan to install 200 MB of available disk space on the system drive A hard disk that stores the message queue database on with at least 500 MB of free space.

 The recommended hardware requirements for Exchange 2013 servers vary depending on a number of factors including the server roles that are installed and the anticipated load that will be placed on the servers.

Operating System Requirements 

The following table lists the supported operating systems for Exchange 2013.

Operating System Requirements  The following table lists the supported operating systems for Exchange 2013. Important:   Microsoft doesn’t support the installation of Exchange 2013 on a computer that’s running in Windows Server Core mode. The computer must be running the full installation of Windows Server. If you want to install Exchange 2013 on a computer that’s running in Windows Server Core mode, you must convert the server to a full installation of Windows Server by doing one of the following:   Windows Server 2008 R2   Reinstall Windows Server and select the Full Installation option. Windows Server 2012   Convert your Windows Server Core mode server to a full installation by running the following command. Supported operating systems for Exchange 2013  Component Requirement Mailbox and Client Access server roles One of the following: Windows Server 2012 Standard or Datacenter Windows Server 2008 R2 Standard with SP1 Windows Server 2008 R2 Enterprise with SP1 Windows Server 2008 R2 Datacenter RTM or later Management tools One of the following: Windows Server 2012 Standard or Datacenter Windows Server 2008 R2 Standard with SP1 Windows Server 2008 R2 Enterprise with SP1 Windows Server 2008 R2 Datacenter RTM or later 64-bit edition of Windows 8 64-bit edition of Windows 7 with SP1 Summarized Overview of the whole transition activity.                                                                                                                                                                          High level technical deployment steps those have been explained above is given below in steps Take backup of AD and MS Exchange 2003 Server message store using MS Windows server or 3rd party backup tools. Update AD Schema for MS Windows 2008 or MS Windows 2012 Server using Media of MS Windows 2008 or 2012. Update AD Schema for MS Exchange 2010 Server using MS Exchange 2010 Media (Latest one). Install / Deploy MS Exchange 2010 Standard Server co-existed with MS Exchange 2003 standard Server. Manage routing of emails in a co-existed environment Move mailboxes to MS Exchange 2010 standard server using EMC (Exchange Management Console) or EPS (Exchange PowerShell). Take backup of MS Exchange 2010 Mailbox DB using MS Windows backup / 3rd party backup tools and verify. Demote MS Exchange 2003 Server. Verify MS Exchange 2010 Routing and email management. Update AD Schema using MS Exchange 2013 CU1 / CU2. Prepare Pre-Requisites for MS Exchange 2013 CU2 on a Server that will be first MS Exchange 2013 Server in the organization. Install / Deploy MS Exchange 2013 Standard Server co-existed with MS Exchange 2010 Standard Server Manage Routing of emails in a co-existed Environment. Move mailboxes to MS Exchange 2013 standard server (using Management Console of MS Exchange 2013 Server) Demote / Uninstall MS Exchange 2010 Standard Server. Note: There must be a backup strategy for Mailbox DB on Daily / Weekly / monthly basis to manage mailbox data.