I signed up for Cloudflare a couple days ago and switched my name servers. Ever since then, my email, which runs through Google G Suite, will not allow me to send any email.
Here’s a great help article by domjh that should help you fix the issue
Feel free to ask if you’re unable to get it working or have any more questions!
When you signed up, you should have seen a list of your DNS records. Did they match the list at your website host? G-Suite has a set of email records that may have not been copied over.