Re: [Exim] filtering relay

Hi ianux, on Fri, 28 Mar 2003 11:08:25 +0100 you wrote:

> the thing I want to do :
<snip>
> filtering not from host but from mail adress

It never ceases to amaze me how many people there are who seem to have a
wish to specifically *become* open relays...

"Ianux", it is possible to do this, but an exceedingly bad idea. Doing so
will turn you into an "open relay". Let's say you have a customer
"customer@???" and you allow them to relay, just by checking their
e-mail address. Then, a spammer can come along, pretend to be
"customer@???" and send huge quantities of junk e-mail, through
your server. This is obviously bad for everyone, especially those on the
receiving end but not least yourself - it will quite likely get your
server blocked/blacklisted by many people and waste your bandwidth.

The solution is to use SMTP AUTH - see the authentication section of the
Exim manual for details. This is pretty easy to set up (depending on how
complicated your circumstances are, and what methods you use), and
compatible (in one way or another) with most if not all common mail
clients.


Tim