ProxyAddress class, C#, Exchange 2010, Powershell 2

In C#, I am trying to get the the property on the Exchange mailbox of a user, "EmailAddresses" using powershell 2010. Previously I had code that did it for Powershell 1.0 but it seems that the type of the results returned from the get-mailbox command has changed with regard to this property.

for powershell 1.0, this used to work.

emailaddresses  = ps.Members["EmailAddresses"].Value as Microsoft.Exchange.Data.ProxyAddressCollection;

Now however, it complains that 

ps.Members["EmailAddresses"].Value is a PSMemberInfo.Value

OK, I can grab the string from it using this

ps.Members["EmailAddresses"].Value.ToString();

but I still need the type ProxyAddress for the code varaible emailaddresses.

ProxyAddress() constructo is protected and  I can't see to cast it from string to type ProxyAddress.

I saw in a code sample: http://social.msdn.microsoft.com/Forums/en-US/exchangesvrdevelopment/thread/593e0793-2485-431a-a923-c5acf53bd65a/ where Mangia did this:

Microsoft.Exchange.Data.ProxyAddress externalemailaddr = new Microsoft.Exchange.Data.SmtpProxyAddress(emailmail, true);

Can someone give me pointers to the derived classes of ProxyAddress?

I have searched on the web without success.

Is there a way to construct a new ProxyAddress from a string?

I have to put all the email addresses in the string into a ProxyAddressCollection to make it work again.

Any help or references would be greatly appreciated. This is powershell 2 and Exchange 2010

Thanks in advance.