Yes, it will be your-server-name.tchmachines.com that you want to set the names too for the mail to eliminate the message. Or you can just tell your email client to accept the certificate and that should also stop it.
Not knowing your domain you are probably on a shared server which means the certificate is tied to the server and not your domain. You can eliminate the error setting your mail servers to the ones listed in the certificate.
Welcome to the forums stluc
curl has been disabled on the servers. You can use the php line you have above to run it with cron. It should work. If not please open a ticket with the help desk.
Well, most AV programs don't protect you from malware or spyware. That's why you can't depend on AV software alone. Scan with MalwareBytes, Spybot and AdAware as well as a good AV program (I use Avast).