Tuesday, June 15, 2010

Understanding Address Rewriting

Exchange Server Address Rewrite feature. This feature allows Exchange Administrators to centrally rewrite outgoing SMTP addresses.
For Exchange Server 2003 Address Rewrite additional tool available .In Exchange Server 2007/2010, Address rewrite is natively integrated into the core messaging system in the form of Exchange Management Shell CMD'lets.
Exchange Address Rewrite is the process of rewriting e-mail addresses for all outgoing messages on a special SMTP virtual server (for Exchange Server 2003). Exchange Address Rewrite is especially used in merger or acquisition scenarios where two Exchange organizations are to be merged into one but, until these two organizations are completely merged, every organization uses its own SMTP namespace while for all outgoing SMTP messages the new or unique SMTP address space is used.
We can user address rewriting to external recipients of messaged from your company exchange 2010. It is useful for organization that use third party vendors to providing email support. Customer expect email messages to come from the organization not from third party vendor. It is also use in merger or acquisition scenarios where two Exchange organizations are to be merged into one but, until these two organizations are completely merged, every organization uses its own SMTP namespace while for all outgoing SMTP messages the new or unique SMTP address space is used. You can configure address rewriting agent on the Receive connector and send connector on the HUB/Edge server role.

For Exchange 2003 you can download tool called EXARCFG.EXE from Microsoft:
http://www.microsoft.com/downloads/details.aspx?familyid=c29487ee-ef0a-49f6-a205-f23e0a98f794&displaylang=en

After downloading the tool, simply extract the download package and open a command prompt to use the EXARCFG tool, as shown in the following screenshot.


The EXARCFG parameter –E enables Address Rewrite while the parameter –D disables Exchange Address Rewrite. The only parameter you should pay more attention to is the –V parameter which specifies which Exchange Virtual SMTP Server should be used.

Exchange Address Rewrite in Exchange Server 2007/2010 is already installed with the core messaging subsystem but is not enabled. You have to use the Exchange Management Shell to activate Exchange Address Rewrite.

With Exchange Server 2007/2010 Address Rewrite you can rewrite SMTP addresses based on:
• Single Address
• Single Domain
• Multiple Subdomains

How to enable Address Rewrite for a Single Address

New-AddressRewriteEntry -name "dinesh@training-cgroup.com to dinesh@dgroup.com" -InternalAddress dinesh@training-cgroup.com -ExternalAddress dinesh@dgroup.com Single Domain

How to enable Address Rewrite for a Single domain
New-AddressRewriteEntry -name "training-cgroup to dgroup" -InternalAddress training-cgroup.com -ExternalAddress dgroup.com

How to display Address Rewrite entries after configuring some entries

Get- AddressRewriteEntry

You can also use address rewriter with in a organization when you have multiple subdomain like in your organization Dgroup.com, if outbond message from us.Dgroup.com, europ.Dgroup.com and asia.Dgroup.com domains are rewritten to appear as if they all originate from single Dgroup.com domain, all message are rewritten as they pass through Edge server that provide SMTP connectvity the whole organization and internet.

When orgazations merge or are acquired. A acquired company may continue to run as a separate business unit, but email administrator can use address rewriting to make the two organizations appear as if theyare one integrated organization. Dgroup, ltd wants all outbound messages from the Cgroup's exchange organization to appear as if they originate from Dgroup, all messages from both organization are sent through the Edge transport servers at Dgroup, ltd, where all messages are rewritten from abc@Cgroup.co to abc@Dgroup.com

Address rewriting agents rewrite e-mail addresses by rewriting the SMTP headers on e-mail messages that are sent and received by an Edge Transport server. Address Rewriting agents typically rewrite outbound messages because the organization wants to hide the internal domains and subdomains as effectively as possible and present a single external domain to the Internet. Address Rewriting agents typically rewrite inbound messages to route those messages to their intended recipients. For these reasons, Address Rewriting agents rewrite several SMTP header fields on outbound e-mail messages. Address Rewriting agents rewrite only one SMTP header field on inbound e-mail messages.

Address Rewriting agents don't rewrite several SMTP header fields, because address rewriting would break SMTP functionality. For example, changing these SMTP headers could affect message loop detection.

When an e-mail message is outbound from the Exchange 2010 organization, outbound-only address rewriting involves modification of the sender SMTP address only. The Address Rewriting agent is configured only on the Send connector on the Edge Transport server.

* The resulting email address must be unique across the organization.
* A proxy address must be configured on each mailbox that matches the rewritten email address.
* You can use wildcard only in the internal domain, no characters can be in front of the wildcard.

Bidirectional address rewriting modifies the sender SMTP address on e-mail messages that are leaving the Exchange organization and the recipient SMTP address on e-mail messages that are entering the Exchange organization.

When you flatten internal subdomains into a single external domain, you must consider the following factors:

* Unique aliases are required.
* Proxy addresses are required {If you're rewriting e-mail from a non-Exchange 2010 e-mail system, you 
   must create Active Directory mail-enabled contacts for each e-mail address in the non-Exchange 2010 e-
   mail address that's being rewritten.}

Make sure that every e-mail alias that exists across all subdomains is unique. Exchange 2010 doesn't check to verify that every e-mail alias that can be rewritten to a single domain is unique. Contacts may be required.

Please note:

Exchange Address Rewrite is NOT used for sending internal E-Mails from one Exchange Server to another in your Exchange Organization. There is one exception from this rule: All native SMTP clients like Mozilla, Thunderbird or Microsoft Outlook Express use Exchange Address Rewite because these messages will be sent directly to the SMTP driver.

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