Add port number specified by port in properties file to use a different ...

...SMTP port.

Background:
 - Amazon (may be) throttling traffic on port 25 with their SES leading to connection timeouts for ERT
 - They advertise other ports which are not throttled, so we will try one of those
Given that you're already logging a message at `info`, this is probably fine. But this sort of logging is usually more appropriate at `debug`.