Inbound SMTP now responds with UUID

CloudMailin's inbound SMTP servers now respond with a UUID instead of an integer when accepting email. For example, the response will now be:

250 Message accepted 87b1afa5-bdce-44c2-8a17-819cb2ac8afd

We don't expect most users to even notice this change but in case you're parsing the response you'll now see a UUID instead of an integer. This change will help us track messages through our logs and correlate with support requests.

This UUID will also be available in the API or on the incoming status page.