[Greylist-users] Comcast & Greylisting

[Dave Warren]

John W. Baxter wrote:
> Leaving aside the question of whether to greylist by IP or by /24 subnet,
> there are IPs one pretty much has to whitelist, because one's customers want
> mail from them but they are broken--old versions of Communigate, for one, I
> think; Yahoo Groups for another (at least that used to be the case--I've
> recently seen a couple of additional blocks of Yahoo Groups servers which
> don't seem to follow their old idea that any error of any sort meant the
> recipient should be reverted to reading via the web only).
>   
Worse, Yahoo Groups sends each message with a unique MAIL FROM, so every 
single message gets greylisted rather then just once per list or 
something more sensible.

To Yahoo Groups' credit, at least they have bounce management rather 
then pounding on dead address for weeks/months/years.

> There are IPs one might as well whitelist.  Neighbor ISPs, large ISPs, etc.
> They are going to pass greylisting anyhow--why cause delays?  Why cause your
> greylisting database to be larger than needed?
>   

Usually a misunderstanding of how and why greylisting is effective.
> Interestingly, your Comcast list and our Comcast list are pretty much
> disjoint.  I think I need to take a look at ours (several were added to the
> whitelisting database in Oct and Nov of 2004; others in Oct and Nov of 2006,
> and yours).  One more thing to do on a rainy weekend.
>   

It's a shame ISPs don't keep up to date IP lists.  SPF koolaid works 
well too, if you simply whitelist by sender domain where SPF:PASS, but 
only if ISPs bother to create an SPF record.

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