Re: rctpto rejection based on smtp verify?

> Although I could write some scripts to poll the user db at the mail server
> back ends. It would be nice if I could be somewhat lazy have have a plugin
> do this. ;)  Real time checking for each delivery is obviously unworkable,
> but poll then cache with maybe a expiry is still a practical option.  The
> mechanics are probably similar to greylisting.

We're doing real-time checking.  It certainly has a performance hit.  We
tried caching but the hit rate was incredibly low -- the overwhelmingly
vast majority of addresses you'll get are randomly made-up invalid
addresses -- so it wasn't worth the extra code and codepaths and we ripped
it out with no noticeable difference.

I might be able to show you some code but I'd need to get permission, and
it's not really very good code anyway ;)

-Jared