Hi,
I would question how "real time" that would be for every email for
6k+
domains. If a few have a large client base, or are expecting
responses
from a mass emailing, it might start to take a *while*, unless you've
got
pretty heavy duty equipment and networking.
It's the same thing the downstream server is going to have to repeat in just a moment anyway, but this time it doesn't have to do the other steps. If you are close to capacity already it might push you over the edge - and be worth scripting a way to maintain that frontend virtuser table that makes it a near-instant hash lookup for the relay sendmail. But for the relay it will be a win either way to avoid the much heavier load of spam-scanning stuff to invalid recipients and making the downstream servers construct bounces.
I hadn't looked at it like that, you may be right, the reduction in scanning may provide enough capacity to handle the additional workload from perl. I think that I would prefer to have sendmail do the "rcpt to:" rejection utilising a map as this I think will be the fastest method, so I'll check out the virtusertable approach.
Thanks
S.