I was reminded that one shouldn’t proxy non-web servers through Cloudflare (at least on their free plan). A new client’s setup was a bit different than how we usually do things, having a mail server as their own domain that was a CNAME to the actual mail server. When they switched to Cloudflare’s nameservers, they were having lots of trouble with mail: connecting, sending, receiving, etc. It took me a little while to realize that it was because the CNAME was set to be proxied through Cloudflare (the little orange cloud). Their paid plans do offer a Spectrum service to handle non-web services, but that has to be set up. Their free plans don’t, and only proxy web services over ports 80 and 443.