You are using phpFox version earlier than 4.6.0? Please refer instruction for this article here.

We recommend not using server mail for your site emails. Instead, you should consider using Sendgrid, Sparkpost or
some other transactional mail service. This tutorial will show you how to set SMTP settings for your mail needs, whether
using your server SMTP or transactional mail. Our example is with Sparkpost but we recommend Sendgrid as we have reports
that Sparkpost is restricting Social Network mail.

We put a site Email for From field.

This should be your site email or noreply email for Email field.