OT: Sendmail REJECT or DISCARD preference

[Peter Farrow]

Koopmann, Jan-Peter wrote:
>>>  Someone sends a spoofed spam email to one of my clients the other
>>>       
>> side
>>     
>>>  of my mailscanner, but they get the address wrong.
>>>       
>> Why did you accept this mail for relay in the first place?
>> This is where you go wrong, all the rest is purely your own fault...
>> If one were in the blame-game:-):-).
>> I'm not, I'm more interrested in you getting this right, and beleive
>> me... this will make a marked difference for you.
>> The problem is simple: You are the public MX for these customers, but
>> you don't know their "email address universe". You need setup a method
>> that ensure you do.
>>     
>
> I think finally begin to understand what he is doing... Thanks Glenn.
> :-)
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Well, actually no I don't need to know their users list, thats the 
beauty of this configuration.  To add anti spam to a clients setup I 
simply insert my servers,  I don't need to ask them any questions other 
than where to send it on.   So this is a top solution, very easy for the 
client, and my clients love it, I can anti spam their email without even 
knowing or wanting know anything about their enterprise I just tell them 
to adjust their DNS.  Hence, I do have it very very right indeed.

Could you imagine trying to know about all the users  on each mail 
domain for each client, with 1000s of clients and therefore 100,000s of 
users.... its all about scale and ease of implementation and thats why 
on this type of scale and even small ones a discard is a supremely 
useful solution...

If I wanted to implement a client user list I could always add a 
look/check ahead milter, but why bother this works better, and a look 
ahead would mean I would need to know if their mailbox holder server was 
behind an internet facing smarthost or not to make the check valid or not...

P.