First, sorry the thread got away, I was thinking that the issue was related not trying to steal it... I read my maillogs and see that relaying is denied when I see the attempts. However sometimes I get mail delivery errors for emails I haven't sent? What I was thinking is that someone could do a telnet in to my port 25 and use my domain to send from... (as if the user where from my domain...) Thanks, James For users of Fedora Core releases <fedora-list@redhat.com> wrote: > On Fri, 2004-07-23 at 12:23, James Marcinek wrote: > > I'm no expert at this but I did some reading and was under the > > impression that people will use your mail server to send emails and > > that there's not a lot that can be done about it. I would definitely > > like to be proven wrong with this. The simply script something to > > telnet into your mail port and send emails... These emails are > > generated from your server so even setting your email to send only > > from your domain does not protect you. Is anyone listening that could > > shed some more light on this? > > > > Thanks, > > > > James > > What you are describing is an email relay. Most systems today ship with > relaying disabled (including all linux distros that I know of). If you > have an open relay it will be found by the spammers and used. This is > one reason to be very careful and sure of what you are doing when > modifying sendmail or one of the other MTAs available for linux. > > If you have not modified your systems MTA configuration you should be > fine. > > At work I see literally hundreds of attempts per day to relay email > through our mail server. Each one of them is denied. > > If you have any doubts about your servers setup do some reading on your > particular MTA. You can also test this by simply telneting to port 25 > of your server and issuing the following commands when you get a > connection: > > helo testdomain.com > mail from: badspammer@spamu.net > rcpt to: hapless@victim.com > data > this is test data