By nature transactional emails are not grouped like a newsletter campaign, so we offer reports by timeline (start / stop date).
But with a simple tweak in your code, you can group messages by type.
For example, you can group Order emails by tagging the mails with tag: `order`. Or group Reminder emails by tagging the emails with tag: `reminder`.
For each email tag we calculate detailed reporting + detailed email history search.
Combine this with detailed Email Metadata that you can use to identify the specific email back in your application (the metadata is sent back in the webhook call).