Folks,

I have a SCSM installed on my environment, and the end-users can open Incidents using Web Portal. But, I have some users in another domain, without relationship with SCSM domain, and we need this users using Web Portla to open Incidents also.

What we can do?

   Well they can create incidents by emailing to SCSM.

   When they would email to SCSM, a new user would be automatically created in CMDB against that user (check setting on exchange connector 3.1 for this).

   If the portal use is must then you will have to provide them with user account on your domain to use to login to portal and submit incident from that account (which is workaround)

If the focus is Web Portal, is there a way to use ADFS to do some integration? Any idea?

   ADFS means SSO. With ADFS you indirectly extend a trust to another domain/realm. You would be mapping users then I-e any login from that domain would translate into a seamless login into scsm domain.

   Instead of going that long and complicated route of trust, why don't you enable the AD trust between two domains involved and cover that 2nd domain also in your infrastructure.