Hi All, I've been asked to create an Exchange design for implementing a Common Namepspace ( @company.com ), for 2000+ users, across several independant AD Forests, each with their own Exchange Org ( domain1.com, domain2.com, etc ). Whilst this can be achieved with Internal Relay Domains, this would result in a "Next Hop, by exception" type of mail routing. Eg:- Is their a valid Account in domain 1 > Yes > Mail is delivered; > No > Mail is forwarded to domain 2; and so on... I've also discussed several "Root / Resource" domains uisng a Cloud Exchange Org and Linked Mailboxes, even Office 365 Hosted Exchange. However, my client is adamant that each company must maintin it's existing independant AD Forest and Exchange Org. Basically, we are trying to achieve some sort of Hub & Spoke for Mail Delivery which can re-direct the Common NameSpace to the respective user in the target domain. I've considered ForeFront Identity to perform GAL Synch, but this would result in the target domain to be set as the primary ( reply ) email address and an alias email address of the Common NameSpace, which then prevents the users from sending outbound email as the Common NameSpace, as it's an alias. If you have any idea's using MS Exchange 2010, or know of a 3rd party application, that can re-route mail on a per user basis, whilst automating the updates of the user / contact lists from several AD's, please help... Thanks, Dave

Some of the third party hosted message hygiene solutions can route email on a per user basis. So you would have all email delivered to them, and then they sort out the delivery. It will be very labour intensive to maintain though. The most that you can do natively is the share SMTP address space techniques, which could mean an email passing through numerous servers before being delivered and will mean a lot of junk/spam being passed around because you will be unable to use recipient filtering. It is unfortuante that the client is making the requirement, probably without fully understanding why or what it will (not) achieve. A single environment in a platform neutral location would be the best option, with trusts to deal with the authentication. Management can be shared easily using RBAC. Simon. Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Some of the third party hosted message hygiene solutions can route email on a per user basis. So you would have all email delivered to them, and then they sort out the delivery. It will be very labour intensive to maintain though. The most that you can do natively is the share SMTP address space techniques, which could mean an email passing through numerous servers before being delivered and will mean a lot of junk/spam being passed around because you will be unable to use recipient filtering. It is unfortuante that the client is making the requirement, probably without fully understanding why or what it will (not) achieve. A single environment in a platform neutral location would be the best option, with trusts to deal with the authentication. Management can be shared easily using RBAC. Simon. Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Hi, You can set this up fairly easily, however I would normally recommend as you have, 1 Forest with Exchange and linked mailboxes. When you create the mail enabled users/contacts in the other Forests ensure you give them a targetaddress that is unique to the Exchange Org that they are on. So for example you may have all Exchange platforms using the single SMTP namespace 'contoso.com' via internal relay domains, however if you then give each of the Exchange Orgs another unique domain, example: Forest1 - forest1.contoso.com Forest2 - forest2.contoso.com Forest3 - forest3.contoso.com you can then route mail directly to the relevant exchange platform. So if you have a contact/mail enabled user in a Forest where their mailbox does not reside, when you look at them in the GAL it will show their user@contoso.com email address, but when a mail is sent to them it will get sent to the targetaddress, which would be user@forest1.contoso.com. This will sent the email to the right Exchange Org without it bouncing all around the place - you'll just need Send Connectors specifying the correct routes for each subdomain. FIM does the above as you are probably aware - but at 20 per user CAL it is extremely expensive. Be aware you'll have to setup some sort of Cross Forest public folder replication (InterOrg tool or third party like Quest) if you plan to use Public Folders, and if the users are expected to share free/busy you'll have to setup Federation between Exchange 2010 Forests using the Microsoft Federation gateway. Autodiscover will be a bit of a nightmare also, obviously when inside the domain it will use the SCP as a connection point and will work, but autodiscover externally will only be able to point to one Forest, luckily you can again user the targetaddress to bounce your autodiscover records to the subdomain email address to get it to work for all users across all Forests. Hope that helps. Oliver Oliver Moazzezi | Exchange MVP, MCSA:M, MCITP:Exchange 2010, BA (Hons) Anim | http://www.exchange2010.com | http://www.cobweb.com | http://twitter.com/OliverMoazzezi