greylisting?

Alex Neuman van der Hans alex at nkpanama.com
Sun Apr 16 02:18:50 IST 2006


Res wrote:
> It comes down to how busy your servers are, and how many you might 
> have in the farm. if you run a decent use mail server, i'd forget it. 
> do you rteally want a queue that banks up for tens of thousands 
> because it will not send on for 10 mnis or whatever.
>
Unless, like I mentioned before, you tweak your settings... for example, 
a low enough default (say, 30 seconds), with all the servers in your 
"farm" sharing the same database... And then add forced whitelisting for 
some customers (and SMTP AUTH connections, and perhaps SPF compliant 
servers).
> I've heard it delaying local sent mail up to 4 hours on a few decent 
> sized ISP's, using it with varying MTA,s sendmail, qmail and postfix, 
> all were as useless as the next with greylisting with their use loads, 
> hence none of them use it nemore :)
>
Probably because they couldn't wrap their heads around it - don't want 
to sound presumptuous, but often people plug the plug on these things 
before they should. I've seen people discontinue using MailScanner just 
because they couldn't figure out how to read the config file - which is 
one of the reasons I want to write "the book" in Spanish). Some of these 
problems usually have a difficult initial period where you adapt and 
train the system; afterwards it becomes good enough that it needs 
minimal or no maintenance.
> But if you get 100 messages a day, I guess it wouldnt make much differnce
> if you got mail now or in another 10 mins or so.
>
I have set up greylisting for companies that receive 30 messages per day 
and want to receive within 3 minutes. Greylisting for 30 seconds works, 
and gets rid of a lot of spam. GREET_PAUSE also works great.
> Also if you run mailing lsits  forget it, youll have so many 
> complaints u'll regret even knowing what greylisting was
>
>
Unless you configure your mailing lists to use, for example, a separate 
SMTP process on a separate host/port/whatever, or if you add your 
mailing list to the greylist milter's database.



Again, please don't take this as anything more than an explanation of 
how you can get around the limitations you describe, with only a little 
bit of hard work. I'm not saying "you're wrong", I'm saying "you're 
right, but what you mention *can* be solved with a little hard work" :)

Regards,

Alex


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