Form Data Arrays showing up in some emails only

I have successfully created a form and I have received 10 legit emails from the system with the Name and contact info for each person.
However on at least 3 of the emails, the Name and contact info is showing the data arrays instead of pulling in the name and contact info from the fields that people would fill out.
For example I see this:
Name: {input_name}<br />
Phone: {input_phone}<br />
Email: {input_email}<br />
Contact Preference: {input_contactpreference}<br />
Comments: {input_textarea_comments}<br />

Is this a bug? Maybe a spam bot doing this? Can anyone explain or help me out?

Thanks
D.

Hi corrupterd,

This is most likely a spambot - though the results I get are usually filled with random strings rather than empty :-(

Validation will protect against some of this but not bots without JavaScript enabled. To block those you need to enable server-side validation.

Bob

Okay thanks,
I kind of thought it might be a spambot. What you said makes sense.