upgrade email connection: verify TLS and neutral fake domain name

Right now, it sends "buildserver" has a hostname with a domain name that leaks information about the operator of the server. This is not a real domain name though, it has no DNS. Since this domain name is sent in plain text as part of the SMTP port 25 STARTTLS negotiation, it is better to set this to a neutral name to avoid profiling.

Verifying TLS is a no brainer, since it works.

Done with: sed -i 's,-tls ,-tls --tls-verify --ehlo mail.example.com ,g' templates/*.j2