How to stop email spamming?

[vibhaJ]

Hi Friends,

I am having one contact-us php script.
Here i have used php mail function to send email to admin.
Even-though i have also used captcha coding, admin is still continuously getting spam (dummy texts) contact us emails.
Actually I am not sure how spammers do such activity.
If i use authentication email rather than simple mail function, does it work?
How can i stop such emails?

Any guidance will be appreciated.
Thanks,
Vibha

[Kraai]

Hi

Try to insert a field in your contact form that contain a question to be answered by the person who uses the contact form Make the question in such a way, that the answer is in the question itself, something like: Mary showed 3 fingers from her left hand, how many fingers did she not show" or any thing you can think of, that a human user with normal intelect would be able to answere. Make this field compulsory, and make it match with "two" for an answere of above question example, meaning, if someone answere anything but the correct word "two" then the submit form fails.

The reasoning behind this is, that 90% of the spam on online forms are generated by bots, and bots cannot answere questions like this, and their automatic submissions will fail. It does not guarantee 100% spam free, but the actual humans doing the spam rounds with their own time is far less.

[vibhaJ]

Thanks Kraai for guidance.
I am curious to know if bots can read captcha or not?
As captcha is a image so do they have image reader or something else?

[Kraai]

Yes, capcha can be cracked by bots. Very recently here on Daniweb the capcha was cracked and numerous spam forum posts was the result.

[Batch Devil]

Get your self a Gmail account (Google Mail) there is not as much spam.

PS. I have never had spam since i signed up!