Re: [exim] Greylisting - how do you implement?

Renaud Allard wrote:
> Marc Perkel wrote:
>
>
>> It doesn't require special whitelisting although you could if you wanted
>> to. If the dead IP which is the lowest MX were dead to everyone except a
>> white list that you would set with iptables then you could whitelist.
>> But it's not really necessary. And technically you don't have to have 3
>> IP addresses. All you have to do is point the bogus MX records to any IP
>> with port 25 closed.
>>
>
> You really should control the additional IPs if you want to be sure port
> 25 stays closed. What happens if you point to an IP you don't control
> and someone suddently put an SMTP server on this IP and starts answering
> 5xx errors to all your mails?
>

I wouldn't do that. If that happened then it would bounce a lot of good
email.