How to resolve email deliverability issues and 0% open rates in Protonmail inboxes?

Key findings

• Pixel blocking: ProtonMail blocks tracking pixels by default, leading to 0% open rates even when emails are opened. This is a privacy feature, not necessarily a deliverability failure.
• Inbox placement vs. opens: A 0% open rate does not automatically mean emails are not delivered to the inbox. It often means the tracking pixel is blocked. Verifying actual inbox placement requires direct testing.
• Reputation checks: ProtonMail applies strict filtering, especially for domains or IPs with low sending volumes or limited reputation data. This can lead to emails landing in spam folders.
• Lack of remediation routes: Formal postmaster contact forms or specific remediation processes for ProtonMail are not easily found, making direct appeals for delisting difficult.

Key considerations

• Verify delivery: Set up a ProtonMail account to test inbox placement directly. This bypasses reliance on potentially inaccurate open rate metrics.
• Check email headers: When possible, inspect email headers for clues regarding filtering decisions or issues, as ProtonMail's headers may provide specific error indicators.
• Focus on clicks, not opens: Since open rates are unreliable, monitor click-through rates (CTR) as a more accurate indicator of engagement for ProtonMail recipients.
• Assess sender reputation: Understand how mail providers evaluate sender reputation, particularly if your sending volume to ProtonMail is low. Issues like high bounce rates or blocklistings can negatively affect deliverability (refer to SMTP errors for details).
• Holistic deliverability: Address broader deliverability issues that could be affecting all recipients, not just ProtonMail users.

Key opinions

• Privacy-driven pixel blocking: Many marketers acknowledge ProtonMail's commitment to user privacy, which includes blocking tracking pixels, thereby preventing open rate data collection.
• Focus on clicks: Given the unreliability of open rates, marketers typically observe higher click-through rates from ProtonMail users, indicating engagement despite no open data.
• Reputation sensitivity: ProtonMail can be particularly harsh on IPs or domains without established reputations or significant sending volume, often leading to spam placement.
• Limited remediation: Marketers express difficulty in finding formal channels or postmaster contacts for ProtonMail to request remediation or whitelisting.

Key considerations

• Self-testing: Create a ProtonMail account to directly test inbox placement and observe pixel blocking behavior.
• ESP consultation: Check with your Email Service Provider (ESP) to determine if low ProtonMail open rates are a known issue on their platform. Some providers may have specific insights.
• Header analysis: If possible, obtain and analyze email headers for any specific reasons or indications for mail failing basic reputation checks.
• Broader deliverability: Implement general email deliverability best practices to improve overall inbox placement across all providers, which can indirectly benefit ProtonMail deliverability.

Key opinions

• Pixel blocking is standard: Experts confirm that ProtonMail's privacy focus means tracking pixels are blocked by default, making open rates unreliable for this MBP.
• Focus on deliverability, not opens: The priority should be confirming actual inbox placement, not recorded opens, for ProtonMail subscribers.
• Reputation is paramount: ProtonMail's strict filtering places a higher emphasis on sender reputation and consistent, legitimate sending patterns.
• Authentication is key: Proper implementation of SPF, DKIM, and DMARC is foundational for proving legitimacy to privacy-focused providers.

Key considerations

• Strengthen sender reputation: Maintain a clean list, avoid spam complaints, and ensure consistent sending to improve your domain and IP reputation overall.
• Verify authentication: Ensure your email authentication records are correctly configured and aligned.
• Monitor delivery, not opens: Shift focus to other deliverability metrics like bounce rates and spam folder placement for ProtonMail, as open rates are skewed.
• Proactive monitoring: Regularly monitor your domain reputation across various blocklists and reputation services. According to Mailmodo, this proactive approach is key.

Key findings

• Default pixel blocking: ProtonMail documentation explicitly states that it blocks external images and tracking pixels by default to enhance user privacy. This feature is fundamental to its service and directly impacts open rate reporting.
• SMTP errors as diagnostics: Official support resources, like those for SMTP errors, are critical for diagnosing email delivery problems and understanding why emails might bounce or fail to reach their destination.
• Importance of authentication: Documentation from various sources highlights that authenticating emails with SPF, DKIM, and DMARC is a core requirement for establishing sender legitimacy and improving inbox placement across all mail providers.
• Reputation and engagement: Tracking delivery rates and bounce rates is universally recommended in documentation to identify underlying issues preventing emails from reaching inboxes, emphasizing the importance of a healthy sender reputation.

Key considerations

• Understand privacy impact: Recognize that 0% open rates on ProtonMail are a feature, not a bug, due to pixel blocking, and adjust expectations for engagement metrics accordingly.
• Prioritize authentication: Ensure your email authentication protocols are robustly implemented and fully compliant with industry standards.
• Monitor bounces and spam placement: Focus on deliverability signals that are not reliant on pixel tracking, such as bounce logs and feedback loops, to identify true delivery issues.
• Maintain list quality: Regularly clean your email lists to reduce bounces and improve sender reputation, which is crucial for all mail providers, including ProtonMail.