How To Change The “WordPress@” Email Address
When a user fills out your contact form, the email you get comes from email@example.com. This has to be this way for the form to work properly. Basically, the email is SENT from the form and to successfully send an email it has to be FROM the same domain. It can't be from firstname.lastname@example.org OR email@example.com, it has to be from the same domain and therefore it defaults to firstname.lastname@example.org.
But now, you can customize that to your liking using the WP Better Emails Plugin.