How to use Multi-Valued Custom Attributes in Exchange 2010 SP2

One of the new features in Exchange Server 2010, SP2, is the new ability to use Multi-Valued Custom attributes:

Exchange 2010 SP2 introduces five new multi-value custom attributes that you can use to store additional information for mail recipient objects. The ExtensionCustomAttribute1 to ExtensionCustomAttribute5 parameters can each hold up to 1,300 values. You can specify multiple values as a comma-delimited list.

These attributes (accessible only via the Exchange Management Shell) can be used with most types of recipients, including Mailboxes, Mail Contacts, Remote Mailboxes and Distribution Groups, and you could use them to store all kinds of extra text-based information against accounts.

So, how do you use the new features? Well, if you are using Powershell, you can use them by assigning an array to the new Extension Custom Attribute1 - 5 properties. As an example, I'll create a simple array, assign it to ExtensionCustomAttribute1 property and then retrieve it:

As it's stored as an array, we can then use PowerShell to add extra attributes to it on demand:

In my example, I am using it to record changes. Although it's got limits, it still could be ideal to store a change log of certain actions to an account, such as the date a quota change was applied for example.

By the way, you'll notice the @{Add="Value"} syntax in the example above; if you aren't familiar with the syntax, you can read more here about Using Multivalued Properties in Exchange 2010.

Steve