Track by day - Don't make me guess!
I'm not a developer. So webhooks and APIs aren't for me. How am I supposed to determine how many emails I've sent in a billing period?!? I can't. I can only guess.
Tracking cumulative monthly send (and other data) tells me little. I'd like to be able to track by day or a number of days in the past month so I can see where I'm at with my monthly subscription volume as well as track and compare campaigns.
Mailgun now includes a reporting section that allows you to review your e-mail usage by account/domain.
Nils Magnus commented
I would also like this information available in the interface. Also, I /am/ a developer, so I would also love for this information to be available through a billing API.
I am thinking aggregated billing details that are retained indefinitely, when you don't need the in-depth but short-lived details from the events API.