[Exim] Another wacky question

I'd like to use directors to _verify_ addresses for a particular
domain, but routers when doing actual deliveries..

I've got a host receiving messages that is part of an NIS/YP setup, and
could use the passwd and alias maps to do verifications (and reject
invalid addresses at SMTP time), but /var/spool/mail is mounted on a
different host, and I don't want to NFS mount it (for previously
disussed-to-death reasons)

Is this possible?

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