Best Way to Control Relaying?

[Alex Neuman van der Hans]

Kai Schaetzl wrote:
> Muhammad Nauman wrote on Fri, 12 May 2006 09:22:48 +0500:
>
>   
>> I already have restricted IP'ies in my /etc/mail/access but they also count 
>> up2 about 6000 ip'z
>>     
>
> If you only restrict access this way you *are* an open relay. Only using SMTP 
> AUTH will stop abuse. This may help you:
> http://spam.abuse.net/adminhelp/
>   
What Kai means, more accurately, is that, to _your customers_, you _are_ 
an open relay. This also means that to _viruses_ and _spyware_ running 
on your customers' machines, you _are_ an open relay.

For all intents and purposes... Understand this, this is the important 
part... You *cannot* allow yourself to be an open relay, to *anyone*, 
under *any* circumstances. People must be made responsible for their 
actions, and that's where my second point comes in.

When you change REC_AUTH to REC_FULL_AUTH, what you're doing is asking 
sendmail to add "authenticated user mnauman" instead of "authenticated 
user" to your headers. That way you can know, immediately, who sent the 
e-mail - as opposed to just knowing it was authenticated and having to 
fish through the logs for the specific msg id.