feature request: testmode

[elnygren]

Apparently Mailgun charges for testmode sends too. Could this library implement a testmode setting that can be flipped during unit tests to prevent unnecessary API calls / stubbing HTTP requests?

[zoellner]

I'd suggest to extend this to the point where it doesn't do any api calls but just logs what it would do. Would be helpful for us to turn on during some local test/dev where the mailgun api key is not available

[bojand]

Hello, please take a look #225 and provide some feedback, and I'll merge and publish soon if OK.

[zoellner]

This would work for our use case