Rebuild your address lists and other cool commandlets

http://halfloaded.com/blog/exchange-2007-aliases-have-invalid-data/
Set-AddressList "All Users" -IncludedRecipients MailboxUsers
Set-AddressList "All Groups" -IncludedRecipients Mailgroups
Set-AddressList "All Contacts" -IncludedRecipients MailContacts
Set-AddressList "Public Folders" -RecipientFilter {RecipientType -eq "PublicFolder"}
Set-GlobalAddressList "Default Global Address List" -RecipientFilter {(Alias -ne $null -and (ObjectClass -eq 'user' -or ObjectClass -eq 'contact' -or ObjectClass -eq 'msExchSystemMailbox' -or ObjectClass -eq 'msExchDynamicDistributionList' -or ObjectClass -eq 'group' -or ObjectClass -eq 'publicFolder'))}