How can I improve my email deliverability?

Key findings

• Outdated tools: Many online email testing services, such as those relying on SpamAssassin, provide misleading or unhelpful information as they use outdated filtering criteria. Modern mailbox providers do not typically filter emails based on size, such as the 100KB limit.
• Focus on practices: Email deliverability is primarily determined by your sending habits and adherence to best practices, rather than a single score from a testing tool.
• Testing's role: While testing tools can monitor whether your deliverability efforts are working, they do not inherently improve your inbox placement. They are diagnostic, not curative.
• Sender reputation: Your sender reputation is a critical factor, built over time through consistent, positive sending behavior. This includes low bounce rates, minimal spam complaints, and high engagement.

Key considerations

• Audience consent: Ensure your audience is fully opted-in to receive your emails. Double opt-in processes are highly recommended. Learn more about improving your email reputation and deliverability.
• Relevant content: Send content that is valuable and relevant to your subscribers to encourage engagement and reduce complaints. This is key to improving deliverability and open rates.
• Easy unsubscribe: Provide clear and easy unsubscribe options to prevent recipients from marking your emails as spam.
• Monitor engagement: Regularly monitor your email performance metrics, including open rates, click-through rates, bounces, and complaint rates. Twilio provides best practices for improving email deliverability.

Key opinions

• Tool reliance: Many marketers initially turn to online tools like 'analyze.email' for quick checks, often encountering warnings about issues like email size (e.g., 100KB limit) and questioning their validity.
• Open rate concerns: A common trigger for seeking deliverability advice is a noticeable decline in email open rates, indicating potential spam folder delivery.
• Desire for clarity: Marketers seek effective and up-to-date methods for testing deliverability, expressing a need for tools that aren't outdated.
• Practical application: There's a strong interest in understanding the practical steps and best practices that directly lead to better inbox placement.

Key considerations

• Content length impact: While large email sizes (over 100KB) might get truncated in some inboxes, they generally do not directly lead to being marked as spam by major mailbox providers. Focus on content optimization for large emails.
• List hygiene: Maintaining a clean email list is paramount for enhancing deliverability, as noted by Salesforce in their deliverability insights. Remove inactive or invalid addresses.
• Engagement signals: Mailbox providers prioritize emails that receive positive engagement (opens, clicks, replies) and penalize those that receive negative signals (spam complaints, deletions without opening).
• Email authentication: Proper implementation of SPF, DKIM, and DMARC is fundamental. This technical setup helps verify your sending legitimacy and is key to boosting email deliverability rates.

Key opinions

• Legacy tool issues: Mailbox providers do not use outdated filters like SpamAssassin, making online services based on such technologies unreliable and potentially misleading.
• Best practices over scores: Deliverability is fundamentally about how emails are sent, not about achieving a specific score on a tool. Adhering to best practices will naturally lead to better scores.
• Value of testing: While testing is valuable for monitoring the effectiveness of best practice improvements, it does not, by itself, guarantee inbox placement.
• Tool limitations: Many testing services are not fit for purpose, provide little useful information, and can create a false sense of security or urgency.

Key considerations

• Technical hygiene: Ensure your email authentication mechanisms, including SPF and DKIM, are correctly configured and functioning. This is a foundational step for secure email delivery.
• Google Postmaster Tools: Sign up for and regularly monitor Google Postmaster Tools. This resource provides critical insights into your sender reputation with Gmail, as detailed in our ultimate guide to Google Postmaster Tools.
• Monitoring metrics: Continuously monitor bounces, spam complaints, and feedback loops to identify and address issues promptly. Klaviyo offers useful insights into understanding email deliverability.
• Avoid third-party links: Limit linking to third-party domains (e.g., Google Docs, link shorteners) as this can negatively impact sender reputation.

Key findings

• Authentication standards: Proper configuration of email authentication protocols like SPF, DKIM, and DMARC is universally recommended to verify sender identity and prevent spoofing.
• Domain reputation: A strong sending domain and IP reputation are critical. This is built over time through consistent, positive sending behaviors and minimal negative feedback.
• Subscriber preferences: Respecting subscriber preferences, offering clear opt-in and opt-out options, and maintaining list hygiene are crucial for positive engagement signals.
• Content quality: High-quality, relevant content that avoids spammy triggers is essential for avoiding spam filters.

Key considerations

• IP warming: For new IPs or domains, gradually increase sending volume to build a positive reputation with ISPs, ensuring your messages are accepted. This helps prevent emails from going to spam.
• Monitoring blocklists: Regularly check if your IP or domain is listed on any email blocklists (or blacklists), as this severely impacts deliverability. Our guide to email blacklists provides more detail.
• Compliance: Comply with email regulations such as CAN-SPAM, GDPR, and other regional laws to avoid legal issues and maintain trust. Mailchimp provides guidance on email deliverability factors.
• Domain separation: Some documentation suggests registering a subdomain specifically for email activity to isolate your main domain's reputation from email issues.