In the fight against spam more and more ISP's require mail send though the php function to originate from the main domain. The contact form however uses the senders email as "from:" address.
I'd like to see a field in settings to optionally set a fixed "from address" (for example contactform@domain.tld) and use "reply-to" to enable replies to the sender, while still using the fixed from address which is accepted by the isp.