>> I want my Exim platform to act as an external filtering solution, mailboxes
>> being hosted on a remote server. That is,at the ACL level on receiving the
>RCPT
>> TO email address, to have it validate this very address against the remote
>> destination server.
>Why not verify recipient with callout?
Actually, the MX of the recipient's domain is my platform :
INTERNET -----> MY PLATFORM -----> REMOTE SERVER
so I guess a callout verification wouldn't work, because Exim would ask itself.
Am I right ?