Selective relaying is not about controlling who can send mail to your
mailserver.
Selective relaying is about deciding whether or not to accept a message
from someone that your mailserver would have to send somewhere else.
As a gross generalization: Your mailserver will happily accept mail sent
from anyone, as long as the final destination is local.
(In other words, as long as your mailserver doesn't have to send it
anywhere else, and can deliver it locally, it will accept the mail. This
makes sense; otherwise all the mailservers on the internet wouldn't
be able to email you, because they wouldn't be in your 'allowed' list).
The selective relay comes into play when your mailserver recieves
a message from someone, and the final destination of that email is
not local.
For example.
abc.com = 10.1.1.xxx = your company
Lets say you want to let anyone on your company's class C use
your mailserver, so you add the following to your /etc/tcp.smtp:
10.1.1.:allow,RELAYCLIENT=""
.. and then reload it. Ok, now your users @abc.com can use your
mailserver as a relay. This means they are not restricted to only
emailing other @abc.com users; they can use your mailserver to
send mail to @aol.com or @home.com or whatever.
Now lets say they have a friend who uses @xyz.com. You dont
host xyz.com, so you dont add the IP's associated with it to your
/etc/tcp.smtp list. Their friend @xyz.com can still mail your users
@abc.com since @abc.com is LOCAL/on your server, and it doesn't
have to forward the email anywhere.
However, if the user @xyz.com tries to use your mailserver to send
mail to @aol.com, your server will say "hm, @aol.com is not a local
domain, I'd have to connect to another mailserver to deliver that. Let
me see if the user's IP from @xyz.com is in my /etc/tcp.smtp file.
Nope, not there, he must not be authorized to use me as a relay" and
it will reject their message.
This explanation is minimal, and doesn't take into account
RBL's, Spamfilters, badmailfrom, etc, but perhaps it will help
you understand relaying a little better.
Best of luck,
- Jamyn
At 07:09 PM 5/2/01 +0900, =?ks_c_5601-1987?B?wMzI8bq5?= wrote:
>Hi all!
>This is Heepok who managing qmail server on Solaris.
>By the way I have a question about Tcpserver program.
>If I use this program to selective relaying, how other mail servers can
>send mail to this server?
>For example
>On server mail.a.com
>when I configure a smtp.cdb like this,
>192.168.:allow
>192.169.:allow
>
>how <mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED](mail.bora.net-164.124.116.3) can send
>mail to <mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED]?
>I think mail.a.com will refuse connection from mail.bora.net.
>So mail.a.com will not receive any mail from other remote servers.
>Could you explain how I can solve this problem?
>Thank you!
>
