Investigate newsletter confirmation email landing in Outlook Junk

Priority: High

Problem

During testing with an outlook.com address, the newsletter subscription/confirmation invitation email landed in the Junk folder. That can make the subscription flow appear broken and materially reduce successful opt-ins.

Goal

Identify the likely deliverability cause and improve inbox placement using the controls available through Buttondown and the website/domain configuration.

Scope

• Reproduce the signup with a clean Outlook.com test address.
• Inspect sender identity and authentication available through Buttondown, including SPF, DKIM, DMARC, and any custom sending-domain configuration where applicable.
• Review From/Reply-To identity, subject, confirmation copy, links, and other obvious spam signals.
• Check Buttondown deliverability guidance/settings and whether a custom sending domain would materially help.
• Compare behavior with Gmail as a control.
• Document provider-controlled limitations rather than claiming inbox placement can be guaranteed.

Acceptance criteria

• Outlook.com confirmation delivery is tested and results recorded.
• Sender authentication/configuration is verified and any actionable gaps are fixed.
• Gmail is tested as a comparison.
• Any Buttondown configuration changes are documented.
• The final result has no known preventable deliverability misconfiguration, with remaining provider-dependent risk documented.

Start by reproducing the newsletter signup with a clean Outlook.com address, then repeat it with Gmail as a control. Inspect Buttondown sender identity, SPF, DKIM, DMARC, custom-domain settings, and the website/domain configuration; done means results and configuration changes are documented, preventable gaps are fixed, and provider-dependent risk is recorded.