Watch those recipient Policies!!!

Recipient policies can be a showstopper in an Exchange 2003 to Exchange 2010 migration process. Where the Exchange 2003 recipient policies make it impossible to install the Exchange 2010 mailbox server role or Exchange 2010 all together.

One issue is a known issue and has been documented by Microsoft. The issue is that the recipient policies have not been properly configured, in which certain domains are marked to be both authoritive and unauthoritive for the organization. This ussualy happends when you use mutiple recipient policies. It could be that a certain SMTP domains are marked Authoritive in one recipient policy while marked unauthoritive in another. More info can be found here: http://technet.microsoft.com/en-us/library/ee428168(EXCHG.80).aspx

Another issue (which has not been documented) that can arise is that the Exchange 2010 mailbox server failes to install successfully. The Exchange 2010 mailbox server role installation fails and reports following message:
[Quote]
Error:
The following error was generated when "$error.Clear(); $count=0; $ExchangeServers = Get-ExchangeServer -DomainController $RoleDomainController; $minVersion = New-Object -typeName Version -argumentlist "8.0.642.0"; foreach ($server in $ExchangeServers) { $currentVersion = [Version]$server.AdminDisplayVersion; if (($currentVersion -ge $minVersion) -and ($server.IsMailboxServer -eq $true)) { $count++; } } if ($count -eq 1) { Set-OrganizationConfig -DomainController $RoleDomainController; }" was run: "The number of subfilters exceeds maximum allowed number of 100. Processing stopped.".

The number of subfilters exceeds maximum allowed number of 100. Processing stopped.
[UnQuote]

When you check the Exchange setup logs you will see that the error occured when the setup checks the existing recipient policies:

Log File
[03/10/2010 14:43:29.0252] [2] [Microsoft Cmdlet Extension Agent] Found Address List "\".
........................
[03/10/2010 14:43:29.0517] [2] [Microsoft Cmdlet Extension Agent] Found Email Address Policy "XXXXXXXXXXX".
[03/10/2010 14:43:29.0517] [2] [Microsoft Cmdlet Extension Agent] Found Email Address Policy "XXXXXXXXXXX".
[03/10/2010 14:43:29.0845] [2] [ERROR] The number of subfilters exceeds maximum allowed number of 100. Processing stopped.

The issue occurs because one or more Recipient policies contain more than 100 “EnabledEmailAddressTemplates". Microsoft is aware of this limitation and will remove this limit in Exchange 2010 SP1 or SP1 Rollup1. To avoid this limitation, you have to make sure that no recipient policy contains more than 100 “EnabledEmailAddressTemplates". If this is the case, spread the templates over multiple recipient policies. Microsoft also advices to leave the default recipient policy untouched, in which it only contains the SMTP address and the default X500 address for the domain into which Exchange 2003 has been installed. Additional SMTP addresses have to be assigned in additional Recipîent policies, and not the default policy.