how to get the email of the form submitter ?

I have a form on my page. This is a "feedback" form and I expect that the visitor who submits the form is expecting an answer from me. Therefore I put a field on the form named "your email" so that the visitor may put the e-address there. But some do not, due to laziness. I wish to be able to warn them that if there is no email address there will be no reply from me ...
alternatively may I get the email address of the sender without his help, by some jacascript maybe ?

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Check out Charity Kahn's articles on form validation on C|Net Builder.com. Here's one:

www.builder.com/Programming/Scripter/042298/?tag=st.cn.sr1.dir.

adam

[This message has been edited by dahamsta (edited 08-08-99).]