Improve subscription confirmation email readability and visual quality

Priority: High

Problem

The subscription confirmation email with the subject/content around “Confirm your subscription to Engineering Leverage by Mantosh” currently renders with very light-colored text and is difficult to read. The confirmation message is a critical step in the signup flow and should look intentional, accessible, and trustworthy.

Goal

Improve the Buttondown confirmation email so it is clearly readable and visually consistent across major email clients without over-designing it.

Scope

• Capture the current confirmation email rendering in Gmail and Outlook.
• Identify which visual/template settings are controlled by Buttondown.
• Improve text contrast, hierarchy, spacing, confirmation CTA/link clarity, and sender identity where configurable.
• Check both light-mode and dark-mode rendering where the client supports it.
• Keep the message concise and clearly transactional: explain that one action confirms the subscription.
• Coordinate naming with the newsletter-name decision if issue #41 results in a rename.

Acceptance criteria

• Body text has clearly readable contrast in Gmail and Outlook.
• The confirmation action is immediately obvious.
• Light-mode and dark-mode rendering have no materially unreadable text.
• The email looks credible and consistent with the website/newsletter identity.
• The final confirmation email is re-tested as part of the full signup flow.
• Any Buttondown limitations that prevent further styling are documented.

Capture the current confirmation email in Gmail and Outlook, then inspect which visual and template settings Buttondown controls. Check light- and dark-mode rendering through the full signup flow, including the confirmation action and sender identity. Done means readable, credible email output and documented Buttondown limitations; coordinate naming with issue #41 if needed.