Sender email doesn’t match domain

So now the emails via the contact form won’t work

Do you see any particular problem?

Now it does not work at all.

I get this error on the front end when I test it “There was an error trying to send your message. Please try again later.”

On which page on the site do you have the form having the issue?

On the home page, there is a “sign up for our free e-book” section.