Email, everyday, and twice on Sunday. If you just give me an email address, I can put it in my contacts and contact you from the same place I contact everybody else: my email client. And I have a record of the outgoing message, and threading in the client to keep your response and my message associated, etc. I can also use CC, BCC, etc. with email, which I can't quickly and conveniently do with your form. But I don't want to be forced to copy & paste stuff.
So yeah, I come down strongly in favor of an email address.
May I ask what is the aim of fill in an email address when one wants to leave a comment. For example, in this page: http://ux.stackexchange.com/questions/6959/contact-form-or-m..., at the bottom, you can post as a guest, but the email address is necessary.
[+] [-] mindcrime|13 years ago|reply
So yeah, I come down strongly in favor of an email address.
[+] [-] sirtel|13 years ago|reply
[+] [-] fintler|13 years ago|reply
[+] [-] invdevm|13 years ago|reply
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