tlsrpt: mail text may contain a summary

[andreasschulze]

The reports are intended to be consumed by applications that can read and understand the attached report.json.gz

But sometimes also humans read that messages. It would be a value it the text below the intro contain a simple summary

• report domain
• reporter
• total-failure-session-count
• total-successful-session-count
• some timespan information
  the session-counts should refer all policies.

This makes it easy to a human reader to recognize very fast

• the volume
• the failure rate

[wietse-postfix]

People who read email with command-line tools such as mutt might benefit from
a tool that you can pipe an email message into, that rips out the application/tlsrpt+gzip attachment, and that pipes it through base64 -d | gunzip | jq filter-expr...