[BlueOnyx:00525] Spam Problem

[Rodrigo Ordonez Licona]

Hi, We are having trouble with some spammers ,

Emails are getting through even though we have disabled popauthenticated
service.

We have a Blueonyx Fully yummed , If you send an email from a valid address
to that valid address the messages is accepted.

Does anyone know how can we stop this kind of spam:

==========================================

telnet ip.add.re.ss 25
ehlo server
mail from:validuser at mydomain.com
250 2.1.0 validuser at mydomain.com... Sender ok
Rcpt to:validuser at mydomain.com
250 2.1.0 validuser at mydomain.com... Sender ok
Data
354 Enter mail, end with "." on a line by itself

Put spam here

.
250 2.0.0 n1GHbxs2003114 Message accepted for delivery


===========================================

Same happens with out Bluequartz and strongbolt.

Is it safe to change something at
Sendmail.cf at this line ?
O DaemonPortOptions=Port=smtp, Name=MTA

Something like 
O DaemonPortOptions=Port=smtp, Name=MTA, M=Ea


Regards

Rodrigo O
Xnet


P.S. My apologies Gerald