what kind of error happens to delivery when spamc can't connect to spamd?

[Steve Prior]

I'm just switching to using spamd -m10 (and other opts) from spamc from procmail 
from sendmail and am wondering what happens when spamd hits the limit and spamc
can't connect to it.  Does this get all the ay back through sendmail so the
sender knows that transmission failed?  I'm wondering if this means that during
times when I'm getting hit by lots of spam traffic that this will work a little
like greylisting where all email will get an error, but probably only legit
email will try again to get through when the storm is over.  Since these storms
typically come when I wouldn't be getting legit email, if this works it would
affect how I tune the -m parameter.

Thanks
Steve