Dynamic Recipient Verification

Dynamic Recipient Verification (DRV) is a mechanism to validate the recipient of an incoming email with another SMTP server running downstream. Consider a scenario where you filter emails for multiple domains that are then forwarded to more than one SMTP server.


Using DRV, Xeams can check if the recipient of an incoming email is valid and will be accepted by the next SMTP that is supposed to receive the message after it has been filtered by Xeams.

When to use DRV

Consider using DRV when:

  • Your using the Regular SMTP Server to process incoming emails, AND
  • You do not want to create a local user in Xeams, AND
  • You are not using Active Directory/LDAP

How to use it

  • Login as admin to the web interface
  • Click SMTP Configuration under Server Configuration
  • Click the link for DRV on the left hand side

Configuring your actual email server to reject invalid users

Every SMTP server has a different way of rejecting invalid users. Click the appropriate link below corresponding to your server.

DRV Cache

In order to avoid constant connections to your actual email server, Xeams caches the results of DRV. This cache is automatically cleared once in 24 hours. Occasionally, this cache can create problems. Consider the following example:

  • You use MS Exchange for your actual email server
  • You get a new employee. However, before adding this new person in your Exchange, someone sends him/her an email.
  • When the email arrives, Xeams will query Exchange to see if the address exists. Since it has not been added yet to Exchange, Xeams will deny this email and will also add it in its cache.
  • Emails to this recipient will be continuously denied by Xeams until the cache is cleared, which will happen a few hours later

Disabling DRV Cache

Add the following line in server.properties file to disable DRV cache.

Clearing DRV Cache On-Demand

  • Log in as admin to the web interface
  • Click Home. This will change the URL in your browser to something like: operation=60
  • Manually change the URL so it ends like: operation=cdrvc and hit enter