How to stop spammers

[phile]

Hi,

I have sendmail 8.10.2 installed as default on my Cobalt RaQ4 and am a complete novice. I have recently discovered that mail is being sent from my server using a valid domain to ensure the mail is relayed. The entries in the log file are shown like this...

to=<name@domain.com>[URL unfurl="true"]www.virtualsite.com,[/URL] ctladdr=username

name@domain.com being the address the spam is sent to,

http://www.virtualsite.com

being a virtual site on my server which means that all errors and bounces come back to one of our customers and username being a valid user of that virtual site. I have also seen entries in the log file like this...

to=username, relay=username@localhost

How do I stop this happening without denying all relaying? Can I stop all relaying from localhost and ensure that addresses in the format <user@domain.com>

http://www.domain.com

are thrown out?

TIA

Phil

 

[BitFuzzy]

Hello

I'm not sure I'm understanding your question correctly.

But if all you're looking to do is stop 'wouldbe spammers' from using your system as a relay point, while keeping relay available for valid users, I'd recommend pop before smtp.

http://popbsmtp.sourceforge.net/

What this does is validate the sender by requring them to 'check' their mail before allowing them to send.

Once the user has been 'authenticated' the user will have a designated period of time their ip will be allowed to relay.(the default is 30min)

Very easy to configure, and easy to follow directions.

Hope this helps

 

[Doug1936]

It is fairly simple to configure Sendmail to &quot;relay only for authenticated users&quot; and to implement SMTP AUTH to require the sender to not only enter their user name but their password in order to send SMTP traffic. This is just a checkbox in their email client. This will prevent spammers from using your mail system to send out their spew, and get you quickly listed in one or more blacklists, which will block your legitimate mail. Implementing POP before SMTP is somewhat outdated, and a little more resource intensive than SMTP AUTH.

Secondly, you can filter against open relay spam, by adding the configuration found at

http://www.ordb.org.

You can additionally filter against spam by adding the configuration found at

http://spamcop.net.

These two filters will not slow down your email processing, and they are free as well. Experience shows that very little spam gets past this combination of filters.

The next step which is also easy in Sendmail, is to do anti-virus scanning. There are a number of really good virus scanners that work with sendmail that are available at either no cost, or minimal cost. MSCE, MCSP, Application Service Provider, Web Site and Email hosting.

http://www.clickdoug.com

 

[phile]

Thanks guys, it turned out to be a perl script that was being abused, converted it to PHP and secured it, now all is well. Thanks for your advise I will be implementing this as additional security.