Open Relay Checker before Opening MTA

Neil Pickford neilp at
Sun Feb 10 14:01:41 EST 2002

I hope the speed of their database is better than the 5 minute
response time their web site replies at.  I suspect you would
need a local copy of the blacklist. has the potential
to be a big bottleneck in such a MTA system.

Also don't assume that all real IP addresses have reverse lookup
entries associated with them.  
My ISP (Optusnet) will not enter a reverse DNS entry for my static IP.  
Does that mean I cannot send mail under this system?
I suspect there are many others in such a situation.

Neil Pickford

Doug Palmer wrote:
> Daniel McNamara wrote:
> > Due to a recent ugly incident where one of my work place mail servers was
> > blacklisted for being an open relay (nothing major it was for some reason
> > accepting null <> users to send mail bypassing IP range checks) I found out
> > about a handy place called the Open Relay DataBase.
> >
> >
> Thanks for the site. It's fascinating to watch the various probes trying
> things I'd never have dreamed of.
> --
> Doug Palmer   doug at

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