Author: Marc Sherman Date: To: exim-users Subject: Re: [exim] Hostnames
Steffen Heil wrote: > Hi
>
> Is there a valid reason for a mail server to connect to my mailserver from
> the same ip with different hostnames (as told in helo/ehlo)?
> I am thinking about blacklisting ips that tell me more then 3 hostnames from
> the same ip within less than 24 hours for about a week.
>
> Every legal mailserver I know always connects using the same helo name.
> But a lot of spammers connect multiple times using different helo names from
> the same ip.
People often ask on this list about how to set the EHLO name dynamically
based on the virtual domain of the sending address. They're usually
cautioned against it, but I've seen the question asked often enough to
assume that there must be legitimate servers doing this in the wild.
