An unfortunate side effect of spam filters is they can treat website form mail as spam. This is because the email in the “From” field (which your visitor fills out so you can email them back) is not from the website in which the form is sent from (your website sends the form, sort of as it’s own personal mail server). The spam filter at your ISP (Internet Service Provider) does not like that setup and so it can often mark your form mail as spam. So when you find your website form mail in the spam trash – it’s your spam filter doing that – not your website.
In addition, your webmaster can work with your ISP, so that your form mail is “White listed” and not trashed by the spam filters before you can even see it.