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Re: Struggling to understand the concept of smtpd_recipient_restrictions

bfyongshinyang.com.my
Date: Fri Mar 17 2006 - 06:40:27 CST

thanks a lot !

> Yong Bong Fong wrote:
>
>> I have read through many articles but I am still confused with the
>> idea of smtpd_recipient_restrictions..
>
> I sympathise - I find a lot of the mail processing that postfix does
> hard to understand; partly because I'm not that familiar with SMTP but
> also because I'm not that aware of all the problems that can occur.
> Thankfully the postfix team have great insite into these things.
>
>> If thats, the case, it means as long as the address come from
>> abcabc.com, then postfix will reject it regardless of what value is in
>> rcpt_to.
>> In this case, although the smtpd_recipient_restrictions say it does
>> restriction on the rcpt to value, in doing its job like above, it
>> doesn't really care who is the rcpt to, am I right or I am wrong?
>
> The restrictions are applied at the stage in the SMTP processing that
> their name implies but any rejecting does not happen until after the
> recipient checks. So it's common, but not essential, to put all the
> tests at the last stage.
>
> Here's what Jim Seymour says in his anti-UCE cheat-sheet
> (http://jimsun.linxnet.com/misc/postfix-anti-UCE.txt):
>
> <QUOTE>
> # Lastly: You'll observe that all of my anti-UCE checks are under
> # smtpd_recipient_restrictions, instead of having a separate
> # smtpd_client_restrictions, etc. This is because, unless you have
> # set smtpd_delay_reject = no (default is "yes"), no rejecting takes
> # place until after RCPT TO anyway. It's easier, cleaner and more
> # predictable when all of the anti-UCE stuff is under recipient
> # restrictions.
> </QUOTE>
>
> It's worth working through Jim's examples as well as for, example, Ralf
> Hildebrandt's venerable "The Book of Postfix" in some detail.
>
> Dick
>
>
>

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