The Contact Form 7 plugin is the defacto standard for contact forms under WordPress. We install the below contact form either on the homepage or if your webpage has one, on the contact page. The name, email, and subject fields are mandatory, the message is optional. The form is protected by an invisible Google ReCaptcha.
The Submit button triggers an email to the info@yourdomain.com address with the contents of the form in the email body and informs the user that the message has been sent.
The plugin Flamingo, from the same developer as Contact Form 7, saves all messages through contact forms into the database. Otherwise, you may lose important messages forever if your mail server has issues or you make a mistake in mail configuration. It keeps an email address book and a list of all messages with detailed information which you can look up in WordPress anytime.