Hi,
I run a small website, and the customers need to contact me from our website,
and I run sendmail, but I get lots of spam, they use my sendmail to send spam,

here is the ps aux:
all those url are spam url, and slow my vps down..
I believe I need to use SMTP to accept connect so that my customers can contact us from our website, (plz correct me if i'm wrong..I'm new to those stuff..)
by the way, we did not need to receive any email from the sendmail server,

Need help asap to protect... our sendmail server.
any simple way to protect our smtp port?

root 20294 0.0 0.0 69160 1520 ? Ss Mar30 0:03 sendmail: MTA: accepting connections
root 16178 0.0 0.1 70052 4172 ? S 17:49 0:00 \_ sendmail: MTA: ./p2VL5q5l009319 kjkak.com.: user open
root 3096 0.0 0.1 70040 4196 ? S 17:59 0:00 \_ sendmail: MTA: ./p2VKGFSh009544 rabota.com.: user open
root 17724 0.0 0.1 69840 3800 ? S 18:09 0:00 \_ sendmail: MTA: ./p31Akbq0028347 donien.info.com.: user open
root 31959 0.0 0.1 70056 4176 ? S 18:19 0:00 \_ sendmail: MTA: ./p31HmQhA001467 rector.freemailservice.info.com.: user open
root 13328 0.0 0.1 69728 3744 ? S 18:29 0:00 \_ sendmail: MTA: ./p31HoSno007543 eladia.freemailservice.info.com.: user open

First you need to check whether you are have open relay :
http://www.checkor.com/

If that report is not ok, then check to see whether you have restricted smtp to localhost only:
http://www.notesbit.com/index.php/sc...-installation/

Finally, if you don't need to send email from your server, then turn off sendmail completely.
You can check if the port is listening : http://www.canyouseeme.org/

You don't say how you are allowing contact to be made. Is it a form that uses sendmail, or are you using a mailto link ? If it's using mailto or you are leaving a visible email address then spam is a fact of life, as is fake "from" addresses. Consider using gmail as your mx provider :
http://www.google.com/apps/

I try to telnet with port 25 (with my ip), but I can't make the connection..I think I did not accept outside connection on port 25,
and I telnet to localhost with port 25, I can make the connection,
by default sendmail is only accepting localhost connection?

how is possible someone can make the connection from outside world?

can anyone explain what the following mean?...
root 20294 0.0 0.0 69160 1520 ? Ss Mar30 0:03 sendmail: MTA: accepting connections
root 16178 0.0 0.1 70052 4172 ? S 17:49 0:00 \_ sendmail: MTA: ./p2VL5q5l009319 kjkak.com.: user open
root 3096 0.0 0.1 70040 4196 ? S 17:59 0:00 \_ sendmail: MTA: ./p2VKGFSh009544 rabota.com.: user open
root 17724 0.0 0.1 69840 3800 ? S 18:09 0:00 \_ sendmail: MTA: ./p31Akbq0028347 donien.info.com.: user open
root 31959 0.0 0.1 70056 4176 ? S 18:19 0:00 \_ sendmail: MTA: ./p31HmQhA001467 rector.freemailservice.info.com.: user open
root 13328 0.0 0.1 69728 3744 ? S 18:29 0:00 \_ sendmail: MTA: ./p31HoSno007543 eladia.freemailservice.info.com.: user open