Another sendmail relaying problem.

[Franco]

Hi, i say that someone is able to bounce a message through my
server to local user, it can use the server smtp to delivery
to local user but the mail from must be any local user.

Example: on my server i have 20 local users, one of this
is pippo at ppppp.com, someone send e-mail through my server using
my server smtp and in the from address of e-mail put pippo at ppppp.com
it send the e-mail without problem.
So all who want do spamming on my local user can do this.
How can stop it?



Scot L. Harris ha scritto:

> On Fri, 2004-06-25 at 12:23, Franco wrote:
> 
>>Hi, i have set relay for my server, i have enabled just few
>>ip of my lan to relay and all work fine.
>>The problem is that if anyone from the internet write to a
>>local user and use the smtp of my server it permit the relay.
>>How can i stop this ?!
>>Best regards.
> 
> 
> Not sure I understand the question?  
> 
> If an external mail server sends email to a local user which is located
> on your server then it is not relaying.  Sendmail accepts the message
> from port 25 and if it is a local user then the message is delivered.  
> 
> Relaying occurs when you connect to an MTA and send a message for
> someone that does not reside on that server.  In general you do not want
> to relay mail, at least not as an open relay (which used to be the
> default configuration a long time ago).  
> 
> If you are saying that someone is able to bounce a message through your
> server to another destination then you have miss-configured the server.