While running Exchange 2010 SP1, We recently came across the error below after attempting to add a mailbox database copy using the Exchange Management Console:

Solution:
Add the database copy using the Exchange Management Shell with the Add-MailboxDatabaseCopy command
We came across an issue recently where we have a few alerts flagged up on our monitoring system (SCOM 2007 R2) in regards to the below Exchange error.
Object [CN=Test,OU=Test,DC=Test,DC=com]. Property [HomeMtaServerId] is set to value [Test.com/Configuration/Deleted Objects/Microsoft MTA
DEL:Guid], it is pointing to the Deleted Objects container in Active Directory. This property should be fixed as soon as possible.
The issue is as said above that the HomeMTA value is set to deleted objects.
You can run the following in the Exchange Management Shell to quickly resolve the issue, add the username above into the below PowerShell command. This will correct the HomeMTA value to the correct setting.
Get-Mailbox “MailboxMentionedAbove” | update-recipient
Skype Beta has been released today and is now available for download from the Marketplace for your Window 7.5 Phone . You can download via the following link http://www.windowsphone.com/en-US/apps/c3f8e570-68b3-4d6a-bdbb-c0a3f4360a51 
February 23rd, 2012
paulw
Note: This blog is written as if you are migrating a user from Windows XP with Office 2003 to Windows 7 with Office 2010.
If are migrating a user to a new computer coupled with an upgrade to Outlook 2003 you can import the nickname file from Outlook 2003 into the new Outlook 2010 suggested contacts:
1. Copy the NK2 file from the old machine which is usually located in C:/Documents and Settings/USERNAME/Application Data/Microsoft/Outlook. This file may be hidden and is called the same as the Outlook profile.
2. Put the NK2 file in the following location on the new PC. %appdata%\Microsoft\Outlook
3. Open control panel –> Mail and click on the Show Profiles button:

4. While the mail profile list is open, click on Start –> Run and type in outlook.exe /importnk2 and click on OK
This should launch Outlook and import the addresses into the Suggested Contacts and the users should see the addresses appear from their old Outlook:

Cheers
Paul
In Exchange 2010, applying impersonate permissions to a service account is achieved by using Role-Based Access Control (RBAC). See the below command to grant the permissions:
New-ManagementRoleAssignment –Name:FriendlyAssignmentName –Role:ApplicationImpersonation –User:serviceAccount
February 22nd, 2012
paulw
During a recent migration of Exchange 2003 to Exchange 2010 we needed to find out how many users had a mailbox and were not disabled.
In the end I used Active Directory Users and Computers snap in to create a saved Query.
1. Open ADUC and right click on Saved Queries and chose new –> Query
2. Give it a name and click on Define Query button
3. Select Custom Search from the drop down menu and then click on the Advanced tab:

4. In the box put in the following:
(&(&(&(!UserAccountControl:1.2.840.113556.1.4.803:=2)(msExchHomeServerName=*)(objectClass=User))))
5. Click on Ok and the query should fetch out all users with mailboxes in Exchange 2003 and that are not disabled.
Cheers
Paul
Just a quick blog on how you can allow a Distribution Group to receive mail from External Users in Exchange 2010/2007
1. Open the Exchange Management Console
2. Expand Recipient Configuration > Distribution Group
3. Right Click Distribution Group you need and choose properties

4. Go to the Mail Flow Settings Tab > Select Message Delivery Restrictions and choose properties
5. Un-tick “Require that all senders are authenticated”
6. Press ok
You will now receive mail from External users to your Distribution Group 
We had an issue recently when upgrading our Exchange Server to Exchange 2010 SP2. Basically the issue was that the first Exchange server we were trying to upgrade was not in the same site as the schema master and we got thrown the below error.
“Setup encountered a problem while validating the state of Active Directory: Exchange organization-level objects have not been created, and setup cannot create them because the local computer is not in the same domain and site as the schema master. Run setup with the /prepareAD parameter and wait for replication to complete.”
To work around this you can temporarily add the below registry key this will make the server belong to a different site, we want our Exchange server to connect to the same site as the Schema Master.
- Open RegEdit
- Browse to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Netlogon\Parameters
- Create a REG_SZ entry with the name SiteName
- Set the Value to the site name of the site the Schema Masters in
- Reboot the Server
Once the server is upgraded delete the REG entry and reboot the server and you will have an upgraded Exchange server and everything will be back to normal 
We recently came across an issue where we were unable to restore a deleted Public Folder. We attempted this using ExFolders, MFCMapi and Outlook and received the following errors:
Exfolders:

MFCMapi:

Outlook:

Solution:
Installing Service Pack 2 for Exchange 2010 allowed us to complete the restore with MFCMapi.
Here is a quick simple command you can run to add a mailbox database copy with the lagged copy time already set so you don’t have to go back and set the lagged copy setting after the seeding.
The below command is adding a copy for the mailbox database named “DatabaseName” onto the server ‘LagServer’ and the lag copy is set for 7 days behind (The maximum you can increase this to is 14 Days)
Add-MailboxDatabaseCopy –Identity ‘DatabaseName’ -MailboxServer ‘LagServer‘ -ReplayLagTime 07.00:00:00