We are using Domino 5 servers (soon to be upgraded to 6.5) behind an IIS SMTP gateway. There are SPAM and virus filters on the gateway (GFI Software) and the spam and anti-virus are working well. What is causing the problems are the Directory Harvest and Dictionary attacks that make it past the SPAM filters.
Can the IIS SMTP be configured to use LDAP or another method to verify the destination address of incoming mail with the Domino server and drop any mail destinations not in our address book?
Could someone provide links to documentation of this if it's possible