Apparently spambots have discovered the contact forms my website. I'm considering adding a CAPTCHA, but in the meantime I've been getting dozens of completed website forms in my Gmail account each day. I know I can configure a filter to always allow e-mails from my website to be delivered (i.e., "never send to spam"), but I'm wondering whether there are also larger implications.

At first, I was marking the spam forms as spam because I figured it would block the sender's e-mail address from getting through again. But since then, I've given it some more thought. I know many spam filters use Bayesian filters and other techniques to identify spam based on its content. If I mark all these e-mails as spam, will legitimate e-mails from my website be marked as spam?

Even if I stop marking the messages as spam, I can see another potential problem. My form is pretty standard (in fact, it's probably very similar to other online forms). If I mark my spambot-submitted website forms as spam, will Gmail begin to mark other people's similar-looking messages as spam?