I want to fix two bugs in interactions between other parts of britney
and the email policy. It's not currently easy to do so because we just
run the policy itself manually by creating some fake excuses.
Steal part of the machinery from the autopkgtest tests, and run a few
tests through britney completely. Use a fake SMTP server to record which
emails we sent.
(The port is hardcoded - that might not be so smart.)