SMTPMailSystem::mail throws exception "Invalid address: (to)" instead of returning FALSE

Moved patch from #12 to MR.

While patch applies cleanly to 8.x-1.3 and all tests on the MR passed, manually testing found a error as 8.x-1.3 introduced additional code that expected logger to be a factory instead of the logger object.

Rather than update the code in debug method I have reverted the change to the constructor logic. I think it could be considered outside the scope of this issue and in recent times keeping the factory as the dependency is preferred.

Made comments on the MR -- there are BC issues and I think we can use reflection instead of needing another public method.

Thanks for the review Jakob - I believe I have implemented all the changes requested.