[exim] Is this a good idea?

I have a smarthost that sends incoming email to
another host. I want to check at the smarthost if
incoming email is going to a valid user and reject it
there and then for invalid users. I was thinking about
changing the

  accept domains = +local_domains
         endpass
         message = unknown user
         verify = recipient

I want to replace the "verify = recipient" with

local_parts = /directory/list_of_valid_users

Are there any hidden "gotchas" in doing this?

I want to reject entire email if even one recipient is
invalid; that is, not get delivered to any of the
recipients in the recipients list of the email
message. Would my idea accomplish that task?

I will add that the list of valid users is small.

Thanks,

Guru


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