[aclug-L] Re: Using RBL on Email server

[Dale W Hodge <dwh@xxxxxxxxxxxxxxxx>]

Thanks for everyone's input.

My mail server handles just the mail for my personal use and my small 
business, so I don't have to be quite as concerned as an ISP would be. 
I've been trying out some conservative RBL's but they don't seem to be 
catching enough. Yesterday I added RBL's that cover China since I rarely 
get any legitimate email from there. I've also added a couple that cover 
dynamic addresses that have hit a honeypot, but not any that use 
automated user nominated list generation. So far that seems to be 
working. It's amazing watching the logs and seeing just how much junk 
mail is being rejected.

As far as greylisting goes, I think that'll be my next step. I need to 
read up a bit more on implementing it first. While I wouldn't call all 
this voodoo, it isn't quite the exact science one might hope for. :) 
There seems to be a lot of trial and error to get just things tailored 
just right.

--Dale


Steven Saner wrote:
> 
> As already mentioned, using an RBL to reject mail can be a little dangerous. 
> Maybe not for a personal mail server, but for a corporate/ISP mail server you 
> can start to reject too much legit mail.
> 
> Also already mentioned is greylisting. Greylisting is great. Very effective 
> at 
> stopping spam and stops very little legit mail because the sender side will 
> resend the message again and it will get through. It's downside is that mail 
> gets delayed, which can be a problem.
> 
> So here's the secret. Combine them. Greylist. But only greylist certain 
> messages. Messages that are suspect, such as being on an RBL. You can use 
> more 
> agressive RBLs because the message will get through if it is legit. And most 
> legit mail will not be delayed at all.
> 
> Steve
> 

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