Bug: Text/Table alignment problems on mail metrics summary

The mail notification can appear misaligned in some mail clients, probably for not using monospaced fonts.
An example from gmail:

Perhaps we can include formatting to ensure better visualization on a wider range of mail clients.

Start by locating the mail-notification code that renders the metrics summary and reproduce the Gmail example from the issue. Compare the generated message in Gmail and other affected clients, then identify formatting that keeps the table aligned without relying on monospaced fonts. Done means the summary is consistently readable across the affected mail clients.

Written by the indexing model from the issue text.