Adding an additional email address using PowerShell

Today I have to add an additional SMTP address to some existing user mailboxes.  This is easy enough to do in the Exchange Management Console but can also be achieved using the following PowerShell command:

Set-Mailbox <alias> -EmailAddresses @{Add=’user@domain.com’}

Similarly, addressess can be removed using the following PowerShell command:

Set-Mailbox <alias> -EmailAddresses @{Remove=’user@domain.com’}