Note the following change in behaviour:
JH/18 Bug 1709: When built with TLS support, the tls_advertise_hosts
option now defaults to "*" (all hosts). The variable is now
available when not built with TLS, default unset, mainly to
enable keeping the testuite sane.
If a server certificate is not supplied (via tls_certificate)
an error is logged, and clients will find TLS connections fail
on startup. Presumably they will retry in-clear.
Packagers of Exim are strongly encouraged to create a server
certificate at installation time.
To follow that advice our rc-script creates the required certificate
and the two variables tls_certificate and tls_privatekey are set in
the configuration file.
