diffierent ldap user login problem

[mllife]

I added two domains of ldap, one openldap and one microsoft AD, and the synchronization was successful. My question is, when the email user logs in, how to distinguish between two different domains? I tried to use user@example.com or example\user, but both methods did not work. Moreover, I found that there seems to be no association between RelayDomains and ldap.

 

[mllife]

I find reason of the problem:
mail user login page use this :https://pmg.yourdomain.com:8006/quarantine
this web page can auth with ldap。