how can I prevent hackers from using my ASP forms to send spam?

Don't have the recipient of the email as a parameter passed to the web page. (FormMail.pl is a bad example of spammers using sites to send spams)

Have the recipient hard coded into the web page.

This will not protect the recipient from getting posts from spammers (spam posting is a new kind of spam), but it will reduce the economic value of using your site to send spams.

Also you can look at the referrer argument passed to your web site. If the referrer is not from/in your domain, you may want to not send the email to your recipient.

There is a new class of spam that is being exploited. This new class of spam uses web forms to request information or quotes to send their message.

For example, you may have a web site that has a contact us link or form. Some spammer can look at your form and send you an email that is a spam by doing a HTTP post to your site. They don't know who will get the message, but the message will contain a reference to buy some drugs, refinance your house or a hot stock tip.

By looking at the referrer, you can filter out these types of messages. (On Unix/linux it is $HTTP_REFERRER)

email spoofing will consistently be attainable, i'm afraid. substitute your email handle or password or 'stay with it'. the terrific element you're able to do is stop making use of the universal unfastened email debts that spammers be attentive to a thank you to spoof, etc.

How are they going to send it? If you use email or data transfer to a database you should limit the receiving locations. then your pages are no use to spammers.

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