Thanks for the quick reply Sebastien.
It seems that the answer may be a bit more complicated than that. In the end I was able to get email sending to work after I subscribed to a 3rd party SMTP service.
As I understand it you can send smtp emails, providing that the outbound port is port 25. In my case I was trying to use gmail as a host which needs to use either the TLS or SSL ports (i.e. not 25). Once I had a 3rd party service that accepted
emails on port 25, it seems happy now.
Hopfully this info will help others having the same problem.