Sylvain,

I recommend you call our support department and we can get it working the way you like. You can either call us or send us an email.

Answers to your questions are following:

• Authentication is not required for inbound email. As long as the recipients email address is valid, Xeams will accept it.
• There are 3 ways to check if a user is valid:
  1. A local user exists in Xeams
  2. A local user exists in Exchange and the DRV feature is configured to check with Exchange
  3. You integrate Xeams with Active Directory