I have a barracuda 300 series and it says that Exchange has an "accelerator" wherein is uses LDAP to verify an email address before sending the mail from the spam filter to the Exchange server. However, I cannot find anything online or in documentation that talks about Exchange having it's own LDAP service. Has anyone ever heard of this? I know I can query my domain controller for LDAP but that won't help me because my DC won't know all the email aliases that exist on the Exchange server. We have Exchange 2007 so I'm really not sure if it exists or if I'm just confused about the whole process. Thanks so much.