Resources needed for greylisting?

Vernon Schryver
Mon Oct 6 16:07:50 UTC 2003

> From: Gary Mills <mills@cc.UManitoba.CA>

> The greylisting feature recently added to DCC sounds attractive.  Can
> anyone tell me what resources, in terms of disk space, memory, and CPU
> would be required for greylisting?  Our mail server accepts between
> 2000 and 20,000 SMTP messages per hour, running on a Sun E450 with 4
> CPUs and 4 gigs of memory.  How many greylist servers would be
> reasonable?

A conservative guess is that a greylist server should be sized
like a private DCC server but using 7/30 day expirations instead of
the default 2/30.  The basic mechanism is the same, dccd and dbclean.
A more reasonable guess is that a greylist server needs to be sized for
the difference between the DCC flooded data and whatever you generate
locally.  For most sites, that's trivial.

> Is there a way to introduce greylisting to an existing DCC installation
> with minimum disruption and user confusion? 

You could run with an embargo of 0 seconds for a week or two.  That 
would mark many of the regular correspondents of your users ok.

>                                              Are their any mail servers
> that react badly to greylisting, and require special treatment?

I don't know of any for which any special treatment is effective.

Vernon Schryver

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