Dynamic Recipient Verification (DRV) is the easiest form of Recipient Verification to use and manage.  To use DRV it is required that your mail server rejects mail addressed to invalid addresses (Recipient Filtering).  SpamTitan can then use your mail server to verify if a recipient specified on an incoming mail is valid or not.  See the links below for guides to enabling Recipient Filtering on common mail server software:

commonly used mail server software:

To configure Exchange 2007


To configure Recipient Filtering for Exchange 2010 see:


If you are using a default standalone (no Edge Transport Server) installation of 2010 the Anti-Spam functionality is not installed. Therefore you need to follow this article:

https://technet.microsoft.com/en-us/library/bb201691(v=exchg.141).aspx to enable it.


For Dynamic Recipient verification to work in Office365, you needed to enable Directory Based Edge Blocking (DBEB) in Office365, so that it reject RCPT TO probes to invalid email addresses..  Once that is enabled, you can enable Dynamic Recipient Verification, and the Verification Server will simply be your Office365 FQDN (just like the Destination Server).

To enable DBEB:  https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/use-directory-based-edge-blocking

To configure Lotus Domino see:


To configure recipient verification in Postfix see:


Once Recipient Filtering is enabled log on to the SpamTitan web interface. Browse to System Setup->Mail Relay->Domains. Edit a domain and select "Dynamic Verification" and enter your mail server IP as the Verification Server.

This will allow SpamTitan to verify the recipient addresses of all incoming mail.  Any mail addresses to invalid addresses will be dropped.  This will aid the spam block rate and keep your daily license usage count accurate.